diff --git a/elements/box.go b/elements/box.go
index d6d3288..63677b2 100644
--- a/elements/box.go
+++ b/elements/box.go
@@ -4,7 +4,6 @@ import "image"
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
 import "git.tebibyte.media/sashakoshka/tomo/shatter"
-import "git.tebibyte.media/sashakoshka/tomo/ability"
 
 var boxCase = tomo.C("tomo", "box") 
 
diff --git a/elements/button.go b/elements/button.go
index 7738712..2aaa1c9 100644
--- a/elements/button.go
+++ b/elements/button.go
@@ -4,9 +4,10 @@ import "image"
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/input"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
-import "git.tebibyte.media/sashakoshka/tomo/ability"
 import "git.tebibyte.media/sashakoshka/tomo/textdraw"
 
+var buttonCase = tomo.C("tomo", "button")
+
 // Button is a clickable button.
 type Button struct {
 	entity tomo.Entity
@@ -26,11 +27,11 @@ type Button struct {
 // NewButton creates a new button with the specified label text.
 func NewButton (text string) (element *Button) {
 	element = &Button { showText: true, enabled: true }
-	element.entity = tomo.NewEntity(element).(buttonEntity)
-	element.theme.Case = tomo.C("tomo", "button")
-	element.drawer.SetFace (element.theme.FontFace (
+	element.entity = tomo.GetBackend().NewEntity(element)
+	element.drawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
+		tomo.FontSizeNormal,
+		buttonCase))
 	element.SetText(text)
 	return
 }
@@ -44,13 +45,13 @@ func (element *Button) Entity () tomo.Entity {
 func (element *Button) Draw (destination artist.Canvas) {
 	state   := element.state()
 	bounds  := element.entity.Bounds()
-	pattern := element.theme.Pattern(tomo.PatternButton, state)
+	pattern := element.entity.Theme().Pattern(tomo.PatternButton, state, buttonCase)
 
 	pattern.Draw(destination, bounds)
 	
-	foreground := element.theme.Color(tomo.ColorForeground, state)
-	sink       := element.theme.Sink(tomo.PatternButton)
-	margin     := element.theme.Margin(tomo.PatternButton)
+	foreground := element.entity.Theme().Color(tomo.ColorForeground, state, buttonCase)
+	sink       := element.entity.Theme().Sink(tomo.PatternButton, buttonCase)
+	margin     := element.entity.Theme().Margin(tomo.PatternButton, buttonCase)
 	
 	offset := image.Pt (
 		bounds.Dx() / 2,
@@ -65,7 +66,7 @@ func (element *Button) Draw (destination artist.Canvas) {
 	}
 
 	if element.hasIcon {
-		icon := element.theme.Icon(element.iconId, tomo.IconSizeSmall) 
+		icon := element.entity.Theme().Icon(element.iconId, tomo.IconSizeSmall, buttonCase) 
 		if icon != nil {
 			iconBounds := icon.Bounds()
 			addedWidth := iconBounds.Dx()
@@ -150,21 +151,11 @@ func (element *Button) ShowText (showText bool) {
 	element.entity.Invalidate()
 }
 
-// SetTheme sets the element's theme.
-func (element *Button) SetTheme (new tomo.Theme) {
-	if new == element.theme.Theme { return }
-	element.theme.Theme = new
-	element.drawer.SetFace (element.theme.FontFace (
+func (element *Button) HandleThemeChange () {
+	element.drawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
-	element.updateMinimumSize()
-	element.entity.Invalidate()
-}
-
-// SetConfig sets the element's configuration.
-func (element *Button) SetConfig (new tomo.Config) {
-	if new == element.config.Config { return }
-	element.config.Config = new
+		tomo.FontSizeNormal,
+		buttonCase))
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
@@ -219,14 +210,14 @@ func (element *Button) HandleKeyUp(key input.Key, modifiers input.Modifiers) {
 }
 
 func (element *Button) updateMinimumSize () {
-	padding := element.theme.Padding(tomo.PatternButton)
-	margin  := element.theme.Margin(tomo.PatternButton)
+	padding := element.entity.Theme().Padding(tomo.PatternButton, buttonCase)
+	margin  := element.entity.Theme().Margin(tomo.PatternButton, buttonCase)
 
 	textBounds  := element.drawer.LayoutBounds()
 	minimumSize := textBounds.Sub(textBounds.Min)
 	
 	if element.hasIcon {
-		icon := element.theme.Icon(element.iconId, tomo.IconSizeSmall) 
+		icon := element.entity.Theme().Icon(element.iconId, tomo.IconSizeSmall, buttonCase) 
 		if icon != nil {
 			bounds := icon.Bounds()
 			if element.showText {
diff --git a/elements/cell.go b/elements/cell.go
index 7032706..2337d65 100644
--- a/elements/cell.go
+++ b/elements/cell.go
@@ -2,8 +2,9 @@ package elements
 
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
-import "git.tebibyte.media/sashakoshka/tomo/ability"
+import "git.tebibyte.media/sashakoshka/tomo/artist/artutil"
 
+var cellCase = tomo.C("tomo", "cell")
 
 // Cell is a single-element container that satisfies tomo.Selectable. It
 // provides styling based on whether or not it is selected.
@@ -20,8 +21,7 @@ type Cell struct {
 // method.
 func NewCell (child tomo.Element) (element *Cell) {
 	element = &Cell { enabled: true }
-	element.theme.Case = tomo.C("tomo", "cell")
-	element.entity = tomo.NewEntity(element).(cellEntity)
+	element.entity = tomo.GetBackend().NewEntity(element)
 	element.Adopt(child)
 	return
 }
@@ -34,11 +34,11 @@ func (element *Cell) Entity () tomo.Entity {
 // Draw causes the element to draw to the specified destination canvas.
 func (element *Cell) Draw (destination artist.Canvas) {
 	bounds  := element.entity.Bounds()
-	pattern := element.theme.Pattern(tomo.PatternTableCell, element.state())
+	pattern := element.entity.Theme().Pattern(tomo.PatternTableCell, element.state(), cellCase)
 	if element.child == nil {
 		pattern.Draw(destination, bounds)
 	} else {
-		artist.DrawShatter (
+		artutil.DrawShatter (
 			destination, pattern, bounds,
 			element.child.Entity().Bounds())
 	}
@@ -49,7 +49,7 @@ func (element *Cell) Layout () {
 	if element.child == nil { return }
 	
 	bounds := element.entity.Bounds()
-	bounds = element.theme.Padding(tomo.PatternTableCell).Apply(bounds)
+	bounds = element.entity.Theme().Padding(tomo.PatternTableCell, cellCase).Apply(bounds)
 
 	element.entity.PlaceChild(0, bounds)
 }
@@ -57,7 +57,7 @@ func (element *Cell) Layout () {
 // DrawBackground draws this element's background pattern to the specified
 // destination canvas.
 func (element *Cell) DrawBackground (destination artist.Canvas) {
-	element.theme.Pattern(tomo.PatternTableCell, element.state()).
+	element.entity.Theme().Pattern(tomo.PatternTableCell, element.state(), cellCase).
 		Draw(destination, element.entity.Bounds())
 }
 
@@ -96,16 +96,6 @@ func (element *Cell) SetEnabled (enabled bool) {
 	element.invalidateChild()
 }
 
-// SetTheme sets this element's theme.
-func (element *Cell) SetTheme (theme tomo.Theme) {
-	if theme == element.theme.Theme { return }
-	element.theme.Theme = theme
-	element.updateMinimumSize()
-	element.entity.Invalidate()
-	element.invalidateChild()
-	element.entity.InvalidateLayout()
-}
-
 // OnSelectionChange sets a function to be called when this element is selected
 // or unselected.
 func (element *Cell) OnSelectionChange (callback func ()) {
@@ -116,6 +106,13 @@ func (element *Cell) Selected () bool {
 	return element.entity.Selected()
 }
 
+func (element *Cell) HandleThemeChange () {
+	element.updateMinimumSize()
+	element.entity.Invalidate()
+	element.invalidateChild()
+	element.entity.InvalidateLayout()
+}
+
 func (element *Cell) HandleSelectionChange () {
 	element.entity.Invalidate()
 	element.invalidateChild()
@@ -145,7 +142,7 @@ func (element *Cell) updateMinimumSize () {
 		width  += childWidth
 		height += childHeight
 	}
-	padding := element.theme.Padding(tomo.PatternTableCell)
+	padding := element.entity.Theme().Padding(tomo.PatternTableCell, cellCase)
 	width  += padding.Horizontal()
 	height += padding.Vertical()
 	
diff --git a/elements/checkbox.go b/elements/checkbox.go
index ed12272..53eb38d 100644
--- a/elements/checkbox.go
+++ b/elements/checkbox.go
@@ -4,9 +4,10 @@ import "image"
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/input"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
-import "git.tebibyte.media/sashakoshka/tomo/ability"
 import "git.tebibyte.media/sashakoshka/tomo/textdraw"
 
+var checkboxCase = tomo.C("tomo", "checkbox")
+
 // Checkbox is a toggle-able checkbox with a label.
 type Checkbox struct {
 	entity tomo.Entity
@@ -23,11 +24,11 @@ type Checkbox struct {
 // NewCheckbox creates a new cbeckbox with the specified label text.
 func NewCheckbox (text string, checked bool) (element *Checkbox) {
 	element = &Checkbox { checked: checked, enabled: true }
-	element.entity = tomo.NewEntity(element).(checkboxEntity)
-	element.theme.Case = tomo.C("tomo", "checkbox")
-	element.drawer.SetFace (element.theme.FontFace (
+	element.entity = tomo.GetBackend().NewEntity(element)
+	element.drawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
+		tomo.FontSizeNormal,
+		checkboxCase))
 	element.SetText(text)
 	return
 }
@@ -51,11 +52,11 @@ func (element *Checkbox) Draw (destination artist.Canvas) {
 
 	element.entity.DrawBackground(destination)
 		
-	pattern := element.theme.Pattern(tomo.PatternButton, state)
+	pattern := element.entity.Theme().Pattern(tomo.PatternButton, state, checkboxCase)
 	pattern.Draw(destination, boxBounds)
 
 	textBounds := element.drawer.LayoutBounds()
-	margin := element.theme.Margin(tomo.PatternBackground)
+	margin := element.entity.Theme().Margin(tomo.PatternBackground, checkboxCase)
 	offset := bounds.Min.Add(image.Point {
 		X: bounds.Dy() + margin.X,
 	})
@@ -63,7 +64,7 @@ func (element *Checkbox) Draw (destination artist.Canvas) {
 	offset.Y -= textBounds.Min.Y
 	offset.X -= textBounds.Min.X
 
-	foreground := element.theme.Color(tomo.ColorForeground, state)
+	foreground := element.entity.Theme().Color(tomo.ColorForeground, state, checkboxCase)
 	element.drawer.Draw(destination, foreground, offset)
 }
 
@@ -103,21 +104,11 @@ func (element *Checkbox) SetText (text string) {
 	element.entity.Invalidate()
 }
 
-// SetTheme sets the element's theme.
-func (element *Checkbox) SetTheme (new tomo.Theme) {
-	if new == element.theme.Theme { return }
-	element.theme.Theme = new
-	element.drawer.SetFace (element.theme.FontFace (
+func (element *Checkbox) HandleThemeChange () {
+	element.drawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
-	element.updateMinimumSize()
-	element.entity.Invalidate()
-}
-
-// SetConfig sets the element's configuration.
-func (element *Checkbox) SetConfig (new tomo.Config) {
-	if new == element.config.Config { return }
-	element.config.Config = new
+		tomo.FontSizeNormal,
+		checkboxCase))
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
@@ -179,7 +170,7 @@ func (element *Checkbox) updateMinimumSize () {
 	if element.text == "" {
 		element.entity.SetMinimumSize(textBounds.Dy(), textBounds.Dy())
 	} else {
-		margin := element.theme.Margin(tomo.PatternBackground)
+		margin := element.entity.Theme().Margin(tomo.PatternBackground, checkboxCase)
 		element.entity.SetMinimumSize (
 			textBounds.Dy() + margin.X + textBounds.Dx(),
 			textBounds.Dy())
diff --git a/elements/combobox.go b/elements/combobox.go
index 549b827..dbd66ca 100644
--- a/elements/combobox.go
+++ b/elements/combobox.go
@@ -7,6 +7,8 @@ import "git.tebibyte.media/sashakoshka/tomo/artist"
 import "git.tebibyte.media/sashakoshka/tomo/ability"
 import "git.tebibyte.media/sashakoshka/tomo/textdraw"
 
+var comboBoxCase = tomo.C("tomo", "comboBox")
+
 // Option specifies a ComboBox option. A blank option will display as "(None)".
 type Option string
 
@@ -36,11 +38,11 @@ type ComboBox struct {
 func NewComboBox (options ...Option) (element *ComboBox) {
 	if len(options) == 0 { options = []Option { "" } }
 	element = &ComboBox { enabled: true, options: options }
-	element.entity = tomo.NewEntity(element).(tomo.FocusableEntity)
-	element.theme.Case = tomo.C("tomo", "comboBox")
-	element.drawer.SetFace (element.theme.FontFace (
+	element.entity = tomo.GetBackend().NewEntity(element)
+	element.drawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
+		tomo.FontSizeNormal,
+		comboBoxCase))
 	element.Select(options[0])
 	return
 }
@@ -54,14 +56,14 @@ func (element *ComboBox) Entity () tomo.Entity {
 func (element *ComboBox) Draw (destination artist.Canvas) {
 	state   := element.state()
 	bounds  := element.entity.Bounds()
-	pattern := element.theme.Pattern(tomo.PatternButton, state)
+	pattern := element.entity.Theme().Pattern(tomo.PatternButton, state, comboBoxCase)
 
 	pattern.Draw(destination, bounds)
 	
-	foreground := element.theme.Color(tomo.ColorForeground, state)
-	sink       := element.theme.Sink(tomo.PatternButton)
-	margin     := element.theme.Margin(tomo.PatternButton)
-	padding    := element.theme.Padding(tomo.PatternButton)
+	foreground := element.entity.Theme().Color(tomo.ColorForeground, state, comboBoxCase)
+	sink       := element.entity.Theme().Sink(tomo.PatternButton, comboBoxCase)
+	margin     := element.entity.Theme().Margin(tomo.PatternButton, comboBoxCase)
+	padding    := element.entity.Theme().Padding(tomo.PatternButton, comboBoxCase)
 	
 	offset := image.Pt(0, bounds.Dy() / 2).Add(bounds.Min)
 
@@ -70,7 +72,7 @@ func (element *ComboBox) Draw (destination artist.Canvas) {
 	offset.Y -= textBounds.Min.Y
 	offset.X -= textBounds.Min.X
 
-	icon := element.theme.Icon(tomo.IconExpand, tomo.IconSizeSmall) 
+	icon := element.entity.Theme().Icon(tomo.IconExpand, tomo.IconSizeSmall, comboBoxCase) 
 	if icon != nil {
 		iconBounds := icon.Bounds()
 		addedWidth := iconBounds.Dx() + margin.X
@@ -138,21 +140,11 @@ func (element *ComboBox) SetEnabled (enabled bool) {
 	element.entity.Invalidate()
 }
 
-// SetTheme sets the element's theme.
-func (element *ComboBox) SetTheme (new tomo.Theme) {
-	if new == element.theme.Theme { return }
-	element.theme.Theme = new
-	element.drawer.SetFace (element.theme.FontFace (
+func (element *ComboBox) HandleThemeChange () {
+	element.drawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
-	element.updateMinimumSize()
-	element.entity.Invalidate()
-}
-
-// SetConfig sets the element's configuration.
-func (element *ComboBox) SetConfig (new tomo.Config) {
-	if new == element.config.Config { return }
-	element.config.Config = new
+		tomo.FontSizeNormal,
+		comboBoxCase))
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
@@ -224,7 +216,7 @@ func (element *ComboBox) dropDown () {
 	menu, err := window.NewMenu(element.entity.Bounds())
 	if err != nil { return }
 
-	cellToOption := make(map[tomo.Selectable] Option)
+	cellToOption := make(map[ability.Selectable] Option)
 
 	list := NewList()
 	for _, option := range element.options {
@@ -250,13 +242,13 @@ func (element *ComboBox) dropDown () {
 }
 
 func (element *ComboBox) updateMinimumSize () {
-	padding := element.theme.Padding(tomo.PatternButton)
-	margin  := element.theme.Margin(tomo.PatternButton)
+	padding := element.entity.Theme().Padding(tomo.PatternButton, comboBoxCase)
+	margin  := element.entity.Theme().Margin(tomo.PatternButton, comboBoxCase)
 
 	textBounds  := element.drawer.LayoutBounds()
 	minimumSize := textBounds.Sub(textBounds.Min)
 	
-	icon := element.theme.Icon(tomo.IconExpand, tomo.IconSizeSmall) 
+	icon := element.entity.Theme().Icon(tomo.IconExpand, tomo.IconSizeSmall, comboBoxCase) 
 	if icon != nil {
 		bounds := icon.Bounds()
 		minimumSize.Max.X += bounds.Dx()
diff --git a/elements/container.go b/elements/container.go
index c483d16..df61e45 100644
--- a/elements/container.go
+++ b/elements/container.go
@@ -1,7 +1,6 @@
 package elements
 
 import "git.tebibyte.media/sashakoshka/tomo"
-import "git.tebibyte.media/sashakoshka/tomo/ability"
 
 type scratchEntry struct {
 	expand     bool
diff --git a/elements/directory.go b/elements/directory.go
index 7c5a882..9234a2d 100644
--- a/elements/directory.go
+++ b/elements/directory.go
@@ -11,6 +11,8 @@ import "git.tebibyte.media/sashakoshka/tomo/shatter"
 // TODO: base on flow implementation of list. also be able to switch to a table
 // variant for a more information dense view.
 
+var directoryCase = tomo.C("tomo", "list")
+
 type historyEntry struct {
 	location string
 	filesystem ReadDirStatFS
@@ -42,8 +44,7 @@ func NewDirectory (
 	err error,
 ) {
 	element = &Directory { }
-	element.theme.Case = tomo.C("tomo", "list")
-	element.entity = tomo.NewEntity(element).(directoryEntity)
+	element.entity = tomo.GetBackend().NewEntity(element)
 	element.container.entity = element.entity
 	element.minimumSize = element.updateMinimumSize
 	element.init()
@@ -59,7 +60,7 @@ func (element *Directory) Draw (destination artist.Canvas) {
 
 	tiles := shatter.Shatter(element.entity.Bounds(), rocks...)
 	for _, tile := range tiles {
-		element.DrawBackground(canvas.Cut(destination, tile))
+		element.DrawBackground(artist.Cut(destination, tile))
 	}
 }
 
@@ -68,8 +69,8 @@ func (element *Directory) Layout () {
 		element.scroll.Y = element.maxScrollHeight()
 	}
 	
-	margin := element.theme.Margin(tomo.PatternPinboard)
-	padding := element.theme.Padding(tomo.PatternPinboard)
+	margin := element.entity.Theme().Margin(tomo.PatternPinboard, directoryCase)
+	padding := element.entity.Theme().Padding(tomo.PatternPinboard, directoryCase)
 	bounds := padding.Apply(element.entity.Bounds())
 	element.contentBounds = image.Rectangle { }
 
@@ -93,7 +94,7 @@ func (element *Directory) Layout () {
 		if width + dot.X > bounds.Max.X {
 			nextLine()
 		}
-		if typedChild, ok := child.(tomo.Flexible); ok {
+		if typedChild, ok := child.(ability.Flexible); ok {
 			height = typedChild.FlexibleHeightFor(width)
 		}
 		if rowHeight < height {
@@ -139,7 +140,7 @@ func (element *Directory) HandleChildMouseDown  (
 	child tomo.Element,
 ) {
 	element.selectNone()
-	if child, ok := child.(tomo.Selectable); ok {
+	if child, ok := child.(ability.Selectable); ok {
 		index := element.entity.IndexOf(child)
 		element.entity.SelectChild(index, true)
 	}
@@ -166,7 +167,7 @@ func (element *Directory) ScrollContentBounds () image.Rectangle {
 // ScrollViewportBounds returns the size and position of the element's
 // viewport relative to ScrollBounds.
 func (element *Directory) ScrollViewportBounds () image.Rectangle {
-	padding := element.theme.Padding(tomo.PatternPinboard)
+	padding := element.entity.Theme().Padding(tomo.PatternPinboard, directoryCase)
 	bounds  := padding.Apply(element.entity.Bounds())
 	bounds   = bounds.Sub(bounds.Min).Add(element.scroll)
 	return bounds
@@ -199,14 +200,11 @@ func (element *Directory) ScrollAxes () (horizontal, vertical bool) {
 }
 
 func (element *Directory) DrawBackground (destination artist.Canvas) {
-	element.theme.Pattern(tomo.PatternPinboard, tomo.State { }).
+	element.entity.Theme().Pattern(tomo.PatternPinboard, tomo.State { }, directoryCase).
 		Draw(destination, element.entity.Bounds())
 }
 
-// SetTheme sets the element's theme.
-func (element *Directory) SetTheme (theme tomo.Theme) {
-	if theme == element.theme.Theme { return }
-	element.theme.Theme = theme
+func (element *Directory) HandleThemeChange () {
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 	element.entity.InvalidateLayout()
@@ -295,7 +293,7 @@ func (element *Directory) selectNone () {
 }
 
 func (element *Directory) maxScrollHeight () (height int) {
-	padding := element.theme.Padding(tomo.PatternSunken)
+	padding := element.entity.Theme().Padding(tomo.PatternSunken, directoryCase)
 	viewportHeight := element.entity.Bounds().Dy() - padding.Vertical()
 	height = element.contentBounds.Dy() - viewportHeight
 	if height < 0 { height = 0 }
@@ -304,7 +302,7 @@ func (element *Directory) maxScrollHeight () (height int) {
 
 
 func (element *Directory) updateMinimumSize () {
-	padding := element.theme.Padding(tomo.PatternPinboard)
+	padding := element.entity.Theme().Padding(tomo.PatternPinboard, directoryCase)
 	minimumWidth := 0
 	for index := 0; index < element.entity.CountChildren(); index ++ {
 		width, height := element.entity.ChildMinimumSize(index)
diff --git a/elements/document.go b/elements/document.go
index 7a23d50..5f92c8c 100644
--- a/elements/document.go
+++ b/elements/document.go
@@ -6,6 +6,8 @@ import "git.tebibyte.media/sashakoshka/tomo/artist"
 import "git.tebibyte.media/sashakoshka/tomo/ability"
 import "git.tebibyte.media/sashakoshka/tomo/shatter"
 
+var documentCase = tomo.C("tomo", "document")
+
 // Document is a scrollable container capcable of laying out flexible child
 // elements. Children can be added either inline (similar to an HTML/CSS inline
 // element), or expanding (similar to an HTML/CSS block element).
@@ -22,8 +24,7 @@ type Document struct {
 // NewDocument creates a new document container.
 func NewDocument (children ...tomo.Element) (element *Document) {
 	element = &Document { }
-	element.theme.Case = tomo.C("tomo", "document")
-	element.entity = tomo.NewEntity(element)
+	element.entity = tomo.GetBackend().NewEntity(element)
 	element.container.entity = element.entity
 	element.minimumSize = element.updateMinimumSize
 	element.init()
@@ -40,7 +41,7 @@ func (element *Document) Draw (destination artist.Canvas) {
 
 	tiles := shatter.Shatter(element.entity.Bounds(), rocks...)
 	for _, tile := range tiles {
-		element.entity.DrawBackground(canvas.Cut(destination, tile))
+		element.entity.DrawBackground(artist.Cut(destination, tile))
 	}
 }
 
@@ -50,8 +51,8 @@ func (element *Document) Layout () {
 		element.scroll.Y = element.maxScrollHeight()
 	}
 	
-	margin := element.theme.Margin(tomo.PatternBackground)
-	padding := element.theme.Padding(tomo.PatternBackground)
+	margin := element.entity.Theme().Margin(tomo.PatternBackground, documentCase)
+	padding := element.entity.Theme().Padding(tomo.PatternBackground, documentCase)
 	bounds := padding.Apply(element.entity.Bounds())
 	element.contentBounds = image.Rectangle { }
 
@@ -82,7 +83,7 @@ func (element *Document) Layout () {
 		if width < bounds.Dx() && entry.expand {
 			width = bounds.Dx()
 		}
-		if typedChild, ok := child.(tomo.Flexible); ok {
+		if typedChild, ok := child.(ability.Flexible); ok {
 			height = typedChild.FlexibleHeightFor(width)
 		}
 		if rowHeight < height {
@@ -135,10 +136,7 @@ func (element *Document) DrawBackground (destination artist.Canvas) {
 	element.entity.DrawBackground(destination)
 }
 
-// SetTheme sets the element's theme.
-func (element *Document) SetTheme (theme tomo.Theme) {
-	if theme == element.theme.Theme { return }
-	element.theme.Theme = theme
+func (element *Document) HandleThemeChange () {
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 	element.entity.InvalidateLayout()
@@ -152,7 +150,7 @@ func (element *Document) ScrollContentBounds () image.Rectangle {
 // ScrollViewportBounds returns the size and position of the element's
 // viewport relative to ScrollBounds.
 func (element *Document) ScrollViewportBounds () image.Rectangle {
-	padding := element.theme.Padding(tomo.PatternBackground)
+	padding := element.entity.Theme().Padding(tomo.PatternBackground, documentCase)
 	bounds  := padding.Apply(element.entity.Bounds())
 	bounds   = bounds.Sub(bounds.Min).Add(element.scroll)
 	return bounds
@@ -185,7 +183,7 @@ func (element *Document) ScrollAxes () (horizontal, vertical bool) {
 }
 
 func (element *Document) maxScrollHeight () (height int) {
-	padding := element.theme.Padding(tomo.PatternSunken)
+	padding := element.entity.Theme().Padding(tomo.PatternBackground, documentCase)
 	viewportHeight := element.entity.Bounds().Dy() - padding.Vertical()
 	height = element.contentBounds.Dy() - viewportHeight
 	if height < 0 { height = 0 }
@@ -193,7 +191,7 @@ func (element *Document) maxScrollHeight () (height int) {
 }
 
 func (element *Document) updateMinimumSize () {
-	padding := element.theme.Padding(tomo.PatternBackground)
+	padding := element.entity.Theme().Padding(tomo.PatternBackground, documentCase)
 	minimumWidth := 0
 	for index := 0; index < element.entity.CountChildren(); index ++ {
 		width, height := element.entity.ChildMinimumSize(index)
diff --git a/elements/file.go b/elements/file.go
index 5b701a9..0c3e105 100644
--- a/elements/file.go
+++ b/elements/file.go
@@ -7,6 +7,8 @@ import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/input"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
 
+var fileCase = tomo.C("files", "file")
+
 // File displays an interactive visual representation of a file within any
 // file system.
 type File struct {
@@ -32,8 +34,7 @@ func NewFile (
 	err error,
 ) {
 	element = &File { enabled: true }
-	element.theme.Case = tomo.C("files", "file")
-	element.entity = tomo.NewEntity(element).(fileEntity)
+	element.entity = tomo.GetBackend().NewEntity(element)
 	err = element.SetLocation(location, within)
 	return
 }
@@ -48,9 +49,9 @@ func (element *File) Draw (destination artist.Canvas) {
 	// background
 	state  := element.state()
 	bounds := element.entity.Bounds()
-	sink   := element.theme.Sink(tomo.PatternButton)
-	element.theme.
-		Pattern(tomo.PatternButton, state).
+	sink   := element.entity.Theme().Sink(tomo.PatternButton, fileCase)
+	element.entity.Theme().
+		Pattern(tomo.PatternButton, state, fileCase).
 		Draw(destination, bounds)
 
 	// icon
@@ -65,7 +66,7 @@ func (element *File) Draw (destination artist.Canvas) {
 		}
 		icon.Draw (
 			destination,
-			element.theme.Color(tomo.ColorForeground, state),
+			element.entity.Theme().Color(tomo.ColorForeground, state, fileCase),
 			bounds.Min.Add(offset))
 	}
 }
@@ -174,7 +175,7 @@ func (element *File) HandleMouseUp  (
 	if button != input.ButtonLeft { return }
 	element.pressed = false
 	within := position.In(element.entity.Bounds())
-	if time.Since(element.lastClick) < element.config.DoubleClickDelay() {
+	if time.Since(element.lastClick) < element.entity.Config().DoubleClickDelay() {
 		if element.Enabled() && within && element.onChoose != nil {
 			element.onChoose()
 		}
@@ -184,17 +185,8 @@ func (element *File) HandleMouseUp  (
 	element.entity.Invalidate()
 }
 
-// SetTheme sets the element's theme.
-func (element *File) SetTheme (theme tomo.Theme) {
-	if theme == element.theme.Theme { return }
-	element.theme.Theme = theme
-	element.entity.Invalidate()
-}
-
-// SetConfig sets the element's configuration.
-func (element *File) SetConfig (config tomo.Config) {
-	if config == element.config.Config { return }
-	element.config.Config = config
+func (element *File) HandleThemeChange () {
+	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
 
@@ -208,11 +200,11 @@ func (element *File) state () tomo.State {
 }
 
 func (element *File) icon () artist.Icon {
-	return element.theme.Icon(element.iconID, tomo.IconSizeLarge)
+	return element.entity.Theme().Icon(element.iconID, tomo.IconSizeLarge, fileCase)
 }
 
 func (element *File) updateMinimumSize () {
-	padding := element.theme.Padding(tomo.PatternButton)
+	padding := element.entity.Theme().Padding(tomo.PatternButton, fileCase)
 	icon := element.icon()
 	if icon == nil {
 		element.entity.SetMinimumSize (
diff --git a/elements/icon.go b/elements/icon.go
index dbb177a..db02085 100644
--- a/elements/icon.go
+++ b/elements/icon.go
@@ -4,6 +4,8 @@ import "image"
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
 
+var iconCase = tomo.C("tomo", "icon")
+
 // Icon is an element capable of displaying a singular icon.
 type Icon struct {
 	entity tomo.Entity
@@ -17,8 +19,7 @@ func NewIcon (id tomo.Icon, size tomo.IconSize) (element *Icon) {
 		id:   id,
 		size: size,
 	}
-	element.entity = tomo.NewEntity(element).(ability.ThemeableEntity)
-	element.theme.Case = tomo.C("tomo", "icon")
+	element.entity = tomo.GetBackend().NewEntity(element)
 	element.updateMinimumSize()
 	return
 }
@@ -37,11 +38,7 @@ func (element *Icon) SetIcon (id tomo.Icon, size tomo.IconSize) {
 	element.entity.Invalidate()
 }
 
-// SetTheme sets the element's theme.
-func (element *Icon) SetTheme (new tomo.Theme) {
-	if new == element.theme.Theme { return }
-	element.theme.Theme = new
-	if element.entity == nil { return }
+func (element *Icon) HandleThemeChange () {
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
@@ -52,8 +49,8 @@ func (element *Icon) Draw (destination artist.Canvas) {
 	
 	bounds := element.entity.Bounds()
 	state  := tomo.State { }
-	element.theme.
-		Pattern(tomo.PatternBackground, state).
+	element.entity.Theme().
+		Pattern(tomo.PatternBackground, state, iconCase).
 		Draw(destination, bounds)
 	icon := element.icon()
 	if icon != nil {
@@ -63,13 +60,13 @@ func (element *Icon) Draw (destination artist.Canvas) {
 			(bounds.Dy() - iconBounds.Dy()) / 2)
 		icon.Draw (
 			destination,
-			element.theme.Color(tomo.ColorForeground, state),
+			element.entity.Theme().Color(tomo.ColorForeground, state, iconCase),
 			bounds.Min.Add(offset))
 	}
 }
 
 func (element *Icon) icon () artist.Icon {
-	return element.theme.Icon(element.id, element.size)
+	return element.entity.Theme().Icon(element.id, element.size, iconCase)
 }
 
 func (element *Icon) updateMinimumSize () {
diff --git a/elements/image.go b/elements/image.go
index 254e876..271a654 100644
--- a/elements/image.go
+++ b/elements/image.go
@@ -15,8 +15,8 @@ type Image struct {
 
 // NewImage creates a new image element.
 func NewImage (image image.Image) (element *Image) {
-	element = &Image { buffer: canvas.FromImage(image) }
-	element.entity = tomo.NewEntity(element)
+	element = &Image { buffer: artist.FromImage(image) }
+	element.entity = tomo.GetBackend().NewEntity(element)
 	bounds := element.buffer.Bounds()
 	element.entity.SetMinimumSize(bounds.Dx(), bounds.Dy())
 	return
diff --git a/elements/label.go b/elements/label.go
index 6853c33..0d28b1b 100644
--- a/elements/label.go
+++ b/elements/label.go
@@ -8,6 +8,8 @@ import "git.tebibyte.media/sashakoshka/tomo/input"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
 import "git.tebibyte.media/sashakoshka/tomo/textdraw"
 
+var labelCase = tomo.C("tomo", "label")
+
 // Label is a simple text box.
 type Label struct {
 	entity tomo.Entity
@@ -25,11 +27,10 @@ type Label struct {
 // NewLabel creates a new label.
 func NewLabel (text string) (element *Label) {
 	element = &Label { }
-	element.theme.Case = tomo.C("tomo", "label")
-	element.entity = tomo.NewEntity(element)
-	element.drawer.SetFace (element.theme.FontFace (
+	element.entity = tomo.GetBackend().NewEntity(element)
+	element.drawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
+		tomo.FontSizeNormal, labelCase))
 	element.SetText(text)
 	return
 }
@@ -58,9 +59,9 @@ func (element *Label) Draw (destination artist.Canvas) {
 	element.entity.DrawBackground(destination)
 
 	textBounds := element.drawer.LayoutBounds()
-	foreground := element.theme.Color (
+	foreground := element.entity.Theme().Color (
 		tomo.ColorForeground,
-		tomo.State { })
+		tomo.State { }, labelCase)
 	element.drawer.Draw(destination, foreground, bounds.Min.Sub(textBounds.Min))
 }
 
@@ -127,21 +128,10 @@ func (element *Label) SetAlign (align textdraw.Align) {
 	element.entity.Invalidate()
 }
 
-// SetTheme sets the element's theme.
-func (element *Label) SetTheme (new tomo.Theme) {
-	if new == element.theme.Theme { return }
-	element.theme.Theme = new
-	element.drawer.SetFace (element.theme.FontFace (
+func (element *Label) HandleThemeChange () {
+	element.drawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
-	element.updateMinimumSize()
-	element.entity.Invalidate()
-}
-
-// SetConfig sets the element's configuration.
-func (element *Label) SetConfig (new tomo.Config) {
-	if new == element.config.Config { return }
-	element.config.Config = new
+		tomo.FontSizeNormal, labelCase))
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
@@ -190,7 +180,7 @@ func (element *Label) updateMinimumSize () {
 	if element.wrap {
 		em := element.drawer.Em().Round()
 		if em < 1 {
-			em = element.theme.Padding(tomo.PatternBackground)[0]
+			em = element.entity.Theme().Padding(tomo.PatternBackground, labelCase)[0]
 		}
 		width, height = em, element.drawer.LineHeight().Round()
 		element.entity.NotifyFlexibleHeightChange()
diff --git a/elements/lerpslider.go b/elements/lerpslider.go
index 5e9eb59..9d62618 100644
--- a/elements/lerpslider.go
+++ b/elements/lerpslider.go
@@ -33,7 +33,7 @@ func NewHLerpSlider[T Numeric] (min, max T, value T) (element *LerpSlider[T]) {
 		min: min,
 		max: max,
 	}
-	element.entity = tomo.NewEntity(element).(tomo.FocusableEntity)
+	element.entity = tomo.GetBackend().NewEntity(element)
 	element.construct()
 	element.SetValue(value)
 	return
diff --git a/elements/list.go b/elements/list.go
index dbae972..db1c006 100644
--- a/elements/list.go
+++ b/elements/list.go
@@ -4,11 +4,15 @@ import "image"
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/input"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
+import "git.tebibyte.media/sashakoshka/tomo/ability"
+import "git.tebibyte.media/sashakoshka/tomo/artist/artutil"
 
 type list struct {
 	container
 	entity tomo.Entity
 
+	c tomo.Case
+
 	enabled       bool
 	scroll        image.Point
 	contentBounds image.Rectangle
@@ -32,8 +36,8 @@ type FlowList struct {
 
 func NewList (children ...tomo.Element) (element *List) {
 	element = &List { }
-	element.theme.Case       = tomo.C("tomo", "list")
-	element.entity           = tomo.NewEntity(element)
+	element.c                = tomo.C("tomo", "list")
+	element.entity           = tomo.GetBackend().NewEntity(element)
 	element.container.entity = element.entity
 	element.minimumSize      = element.updateMinimumSize
 	element.init(children...)
@@ -42,8 +46,8 @@ func NewList (children ...tomo.Element) (element *List) {
 
 func NewFlowList (children ...tomo.Element) (element *FlowList) {
 	element = &FlowList { }
-	element.theme.Case       = tomo.C("tomo", "flowList")
-	element.entity           = tomo.NewEntity(element).(listEntity)
+	element.c                = tomo.C("tomo", "flowList")
+	element.entity           = tomo.GetBackend().NewEntity(element)
 	element.container.entity = element.entity
 	element.minimumSize      = element.updateMinimumSize
 	element.init(children...)
@@ -63,8 +67,8 @@ func (element *list) Draw (destination artist.Canvas) {
 		rocks[index] = element.entity.Child(index).Entity().Bounds()
 	}
 
-	pattern := element.theme.Pattern(tomo.PatternSunken, element.state())
-	artist.DrawShatter(destination, pattern, element.entity.Bounds(), rocks...)
+	pattern := element.entity.Theme().Pattern(tomo.PatternSunken, element.state(), element.c)
+	artutil.DrawShatter(destination, pattern, element.entity.Bounds(), rocks...)
 }
 
 func (element *List) Layout () {
@@ -72,8 +76,8 @@ func (element *List) Layout () {
 		element.scroll.Y = element.maxScrollHeight()
 	}
 	
-	margin := element.theme.Margin(tomo.PatternSunken)
-	padding := element.theme.Padding(tomo.PatternSunken)
+	margin := element.entity.Theme().Margin(tomo.PatternSunken, element.c)
+	padding := element.entity.Theme().Padding(tomo.PatternSunken, element.c)
 	bounds := padding.Apply(element.entity.Bounds())
 	element.contentBounds = image.Rectangle { }
 
@@ -110,8 +114,8 @@ func (element *FlowList) Layout () {
 		element.scroll.Y = element.maxScrollHeight()
 	}
 	
-	margin := element.theme.Margin(tomo.PatternSunken)
-	padding := element.theme.Padding(tomo.PatternSunken)
+	margin := element.entity.Theme().Margin(tomo.PatternSunken, element.c)
+	padding := element.entity.Theme().Padding(tomo.PatternSunken, element.c)
 	bounds := padding.Apply(element.entity.Bounds())
 	element.contentBounds = image.Rectangle { }
 
@@ -135,7 +139,7 @@ func (element *FlowList) Layout () {
 		if width + dot.X > bounds.Max.X {
 			nextLine()
 		}
-		if typedChild, ok := child.(tomo.Flexible); ok {
+		if typedChild, ok := child.(ability.Flexible); ok {
 			height = typedChild.FlexibleHeightFor(width)
 		}
 		if rowHeight < height {
@@ -162,7 +166,7 @@ func (element *FlowList) Layout () {
 
 func (element *list) Selected () ability.Selectable {
 	if element.selected == -1 { return nil }
-	child, ok := element.entity.Child(element.selected).(tomo.Selectable)
+	child, ok := element.entity.Child(element.selected).(ability.Selectable)
 	if !ok { return nil }
 	return child
 }
@@ -221,7 +225,7 @@ func (element *list) HandleChildMouseDown (
 ) {
 	if !element.enabled { return }
 	element.Focus()
-	if child, ok := child.(tomo.Selectable); ok {
+	if child, ok := child.(ability.Selectable); ok {
 		element.Select(child)
 	}
 }
@@ -274,10 +278,7 @@ func (element *list) DrawBackground (destination artist.Canvas) {
 	element.entity.DrawBackground(destination)
 }
 
-// SetTheme sets the element's theme.
-func (element *list) SetTheme (theme tomo.Theme) {
-	if theme == element.theme.Theme { return }
-	element.theme.Theme = theme
+func (element *list) HandleThemeChange () {
 	element.minimumSize()
 	element.entity.Invalidate()
 	element.entity.InvalidateLayout()
@@ -312,7 +313,7 @@ func (element *list) ScrollContentBounds () image.Rectangle {
 // ScrollViewportBounds returns the size and position of the element's
 // viewport relative to ScrollBounds.
 func (element *list) ScrollViewportBounds () image.Rectangle {
-	padding := element.theme.Padding(tomo.PatternSunken)
+	padding := element.entity.Theme().Padding(tomo.PatternSunken, element.c)
 	bounds  := padding.Apply(element.entity.Bounds())
 	bounds   = bounds.Sub(bounds.Min).Add(element.scroll)
 	return bounds
@@ -364,7 +365,7 @@ func (element *list) selectNone () {
 func (element *list) scrollToSelected () {
 	if element.selected < 0 { return }
 	target := element.entity.Child(element.selected).Entity().Bounds()
-	padding := element.theme.Padding(tomo.PatternSunken)
+	padding := element.entity.Theme().Padding(tomo.PatternSunken, element.c)
 	bounds  := padding.Apply(element.entity.Bounds())
 	if target.Min.Y < bounds.Min.Y {
 		element.scroll.Y -= bounds.Min.Y - target.Min.Y
@@ -385,7 +386,7 @@ func (element *list) state () tomo.State {
 }
 
 func (element *list) maxScrollHeight () (height int) {
-	padding := element.theme.Padding(tomo.PatternSunken)
+	padding := element.entity.Theme().Padding(tomo.PatternSunken, element.c)
 	viewportHeight := element.entity.Bounds().Dy() - padding.Vertical()
 	height = element.contentBounds.Dy() - viewportHeight
 	if height < 0 { height = 0 }
@@ -393,8 +394,8 @@ func (element *list) maxScrollHeight () (height int) {
 }
 
 func (element *List) updateMinimumSize () {
-	margin := element.theme.Margin(tomo.PatternSunken)
-	padding := element.theme.Padding(tomo.PatternSunken)
+	margin := element.entity.Theme().Margin(tomo.PatternSunken, element.c)
+	padding := element.entity.Theme().Padding(tomo.PatternSunken, element.c)
 
 	width  := 0
 	height := 0
@@ -427,7 +428,7 @@ func (element *List) updateMinimumSize () {
 }
 
 func (element *FlowList) updateMinimumSize () {
-	padding := element.theme.Padding(tomo.PatternSunken)
+	padding := element.entity.Theme().Padding(tomo.PatternSunken, element.c)
 	minimumWidth := 0
 	for index := 0; index < element.entity.CountChildren(); index ++ {
 		width, height := element.entity.ChildMinimumSize(index)
diff --git a/elements/progressbar.go b/elements/progressbar.go
index 7179153..c4c5308 100644
--- a/elements/progressbar.go
+++ b/elements/progressbar.go
@@ -4,6 +4,8 @@ import "image"
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
 
+var progressBarCase = tomo.C("tomo", "progressBar")
+
 // ProgressBar displays a visual indication of how far along a task is.
 type ProgressBar struct {
 	entity tomo.Entity
@@ -16,8 +18,7 @@ func NewProgressBar (progress float64) (element *ProgressBar) {
 	if progress < 0 { progress = 0 }
 	if progress > 1 { progress = 1 }
 	element = &ProgressBar { progress: progress }
-	element.entity = tomo.NewEntity(element)
-	element.theme.Case = tomo.C("tomo", "progressBar")
+	element.entity = tomo.GetBackend().NewEntity(element)
 	element.updateMinimumSize()
 	return
 }
@@ -31,15 +32,15 @@ func (element *ProgressBar) Entity () tomo.Entity {
 func (element *ProgressBar) Draw (destination artist.Canvas) {
 	bounds := element.entity.Bounds()
 
-	pattern := element.theme.Pattern(tomo.PatternSunken, tomo.State { })
-	padding := element.theme.Padding(tomo.PatternSunken)
+	pattern := element.entity.Theme().Pattern(tomo.PatternSunken, tomo.State { }, progressBarCase)
+	padding := element.entity.Theme().Padding(tomo.PatternSunken, progressBarCase)
 	pattern.Draw(destination, bounds)
 	bounds = padding.Apply(bounds)
 	meterBounds := image.Rect (
 		bounds.Min.X, bounds.Min.Y,
 		bounds.Min.X + int(float64(bounds.Dx()) * element.progress),
 		bounds.Max.Y)
-	mercury := element.theme.Pattern(tomo.PatternMercury, tomo.State { })
+	mercury := element.entity.Theme().Pattern(tomo.PatternMercury, tomo.State { }, progressBarCase)
 	mercury.Draw(destination, meterBounds)
 }
 
@@ -52,17 +53,14 @@ func (element *ProgressBar) SetProgress (progress float64) {
 	element.entity.Invalidate()
 }
 
-// SetTheme sets the element's theme.
-func (element *ProgressBar) SetTheme (new tomo.Theme) {
-	if new == element.theme.Theme { return }
-	element.theme.Theme = new
+func (element *ProgressBar) HandleThemeChange () {
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
 
 func (element *ProgressBar) updateMinimumSize() {
-	padding      := element.theme.Padding(tomo.PatternSunken)
-	innerPadding := element.theme.Padding(tomo.PatternMercury)
+	padding      := element.entity.Theme().Padding(tomo.PatternSunken, progressBarCase)
+	innerPadding := element.entity.Theme().Padding(tomo.PatternMercury, progressBarCase)
 	element.entity.SetMinimumSize (
 		padding.Horizontal() + innerPadding.Horizontal(),
 		padding.Vertical()   + innerPadding.Vertical())
diff --git a/elements/scroll.go b/elements/scroll.go
index a32bc34..cd39609 100644
--- a/elements/scroll.go
+++ b/elements/scroll.go
@@ -6,6 +6,8 @@ import "git.tebibyte.media/sashakoshka/tomo/input"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
 import "git.tebibyte.media/sashakoshka/tomo/ability"
 
+var scrollCase = tomo.C("tomo", "scroll")
+
 // ScrollMode specifies which sides of a Scroll have scroll bars.
 type ScrollMode int; const (
 	ScrollNeither    ScrollMode = 0
@@ -33,8 +35,7 @@ type Scroll struct {
 // NewScroll creates a new scroll element.
 func NewScroll (mode ScrollMode, child ability.Scrollable) (element *Scroll) {
 	element = &Scroll { }
-	element.theme.Case = tomo.C("tomo", "scroll")
-	element.entity = tomo.NewEntity(element).(scrollEntity)
+	element.entity = tomo.GetBackend().NewEntity(element)
 
 	if mode.Includes(ScrollHorizontal) {
 		element.horizontal = NewHScrollBar()
@@ -82,8 +83,8 @@ func (element *Scroll) Draw (destination artist.Canvas) {
 			bounds.Max.X - element.vertical.Entity().Bounds().Dx(),
 			bounds.Max.Y - element.horizontal.Entity().Bounds().Dy())
 		state := tomo.State { }
-		deadArea := element.theme.Pattern(tomo.PatternDead, state)
-		deadArea.Draw(canvas.Cut(destination, bounds), bounds)
+		deadArea := element.entity.Theme().Pattern(tomo.PatternDead, state, scrollCase)
+		deadArea.Draw(artist.Cut(destination, bounds), bounds)
 	}
 }
 
@@ -185,20 +186,12 @@ func (element *Scroll) HandleScroll (
 	element.scrollChildBy(int(deltaX), int(deltaY))
 }
 
-// SetTheme sets the element's theme.
-func (element *Scroll) SetTheme (theme tomo.Theme) {
-	if theme == element.theme.Theme { return }
-	element.theme.Theme = theme
+func (element *Scroll) HandleThemeChange () {
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 	element.entity.InvalidateLayout()
 }
 
-// SetConfig sets the element's configuration.
-func (element *Scroll) SetConfig (config tomo.Config) {
-	element.config.Config = config
-}
-
 func (element *Scroll) updateMinimumSize () {
 	var width, height int
 
diff --git a/elements/scrollbar.go b/elements/scrollbar.go
index 634a5b9..e3424e2 100644
--- a/elements/scrollbar.go
+++ b/elements/scrollbar.go
@@ -4,7 +4,6 @@ import "image"
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/input"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
-import "git.tebibyte.media/sashakoshka/tomo/ability"
 
 // ScrollBar is an element similar to Slider, but it has special behavior that
 // makes it well suited for controlling the viewport position on one axis of a
@@ -20,6 +19,8 @@ import "git.tebibyte.media/sashakoshka/tomo/ability"
 type ScrollBar struct {
 	entity tomo.Entity
 
+	c tomo.Case
+
 	vertical bool
 	enabled  bool
 	dragging bool
@@ -39,8 +40,8 @@ func NewVScrollBar () (element *ScrollBar) {
 		vertical: true,
 		enabled:  true,
 	}
-	element.theme.Case = tomo.C("tomo", "scrollBarVertical")
-	element.entity = tomo.NewEntity(element).(scrollBarEntity)
+	element.c = tomo.C("tomo", "scrollBarVertical")
+	element.entity = tomo.GetBackend().NewEntity(element)
 	element.updateMinimumSize()
 	return
 }
@@ -50,8 +51,8 @@ func NewHScrollBar () (element *ScrollBar) {
 	element = &ScrollBar {
 		enabled: true,
 	}
-	element.theme.Case = tomo.C("tomo", "scrollBarHorizontal")
-	element.entity = tomo.NewEntity(element).(tomo.Entity)
+	element.c = tomo.C("tomo", "scrollBarHorizontal")
+	element.entity = tomo.GetBackend().NewEntity(element)
 	element.updateMinimumSize()
 	return
 }
@@ -70,10 +71,10 @@ func (element *ScrollBar) Draw (destination artist.Canvas) {
 		Disabled: !element.Enabled(),
 		Pressed:  element.dragging,
 	}
-	element.theme.Pattern(tomo.PatternGutter, state).Draw (
+	element.entity.Theme().Pattern(tomo.PatternGutter, state, element.c).Draw (
 		destination,
 		bounds)
-	element.theme.Pattern(tomo.PatternHandle, state).Draw (
+	element.entity.Theme().Pattern(tomo.PatternHandle, state, element.c).Draw (
 		destination,
 		element.bar)
 }
@@ -83,7 +84,7 @@ func (element *ScrollBar) HandleMouseDown  (
 	button input.Button,
 	modifiers input.Modifiers,
 ) {
-	velocity := element.config.ScrollVelocity()
+	velocity := element.entity.Config().ScrollVelocity()
 
 	if position.In(element.bar) {
 		// the mouse is pressed down within the bar's handle
@@ -185,17 +186,7 @@ func (element *ScrollBar) OnScroll (callback func (viewport image.Point)) {
 	element.onScroll = callback
 }
 
-// SetTheme sets the element's theme.
-func (element *ScrollBar) SetTheme (new tomo.Theme) {
-	if new == element.theme.Theme { return }
-	element.theme.Theme = new
-	element.entity.Invalidate()
-}
-
-// SetConfig sets the element's configuration.
-func (element *ScrollBar) SetConfig (new tomo.Config) {
-	if new == element.config.Config { return }
-	element.config.Config = new
+func (element *ScrollBar) HandleThemeChange () {
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
@@ -263,7 +254,7 @@ func (element *ScrollBar) recalculate () {
 
 func (element *ScrollBar) recalculateVertical () {
 	bounds := element.entity.Bounds()
-	padding := element.theme.Padding(tomo.PatternGutter)
+	padding := element.entity.Theme().Padding(tomo.PatternGutter, element.c)
 	element.track = padding.Apply(bounds)
 
 	contentBounds  := element.contentBounds
@@ -290,7 +281,7 @@ func (element *ScrollBar) recalculateVertical () {
 
 func (element *ScrollBar) recalculateHorizontal () {
 	bounds := element.entity.Bounds()
-	padding := element.theme.Padding(tomo.PatternGutter)
+	padding := element.entity.Theme().Padding(tomo.PatternGutter, element.c)
 	element.track = padding.Apply(bounds)
 
 	contentBounds  := element.contentBounds
@@ -316,8 +307,8 @@ func (element *ScrollBar) recalculateHorizontal () {
 }
 
 func (element *ScrollBar) updateMinimumSize () {
-	gutterPadding := element.theme.Padding(tomo.PatternGutter)
-	handlePadding := element.theme.Padding(tomo.PatternHandle)
+	gutterPadding := element.entity.Theme().Padding(tomo.PatternGutter, element.c)
+	handlePadding := element.entity.Theme().Padding(tomo.PatternHandle, element.c)
 	if element.vertical {
 		element.entity.SetMinimumSize (
 			gutterPadding.Horizontal() + handlePadding.Horizontal(),
diff --git a/elements/slider.go b/elements/slider.go
index f2b7ea1..5e67425 100644
--- a/elements/slider.go
+++ b/elements/slider.go
@@ -4,7 +4,6 @@ import "image"
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/input"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
-import "git.tebibyte.media/sashakoshka/tomo/ability"
 
 // Slider is a slider control with a floating point value between zero and one.
 type Slider struct {
@@ -22,12 +21,16 @@ func NewVSlider (value float64) (element *Slider) {
 func NewHSlider (value float64) (element *Slider) {
 	element = &Slider { }
 	element.value = value
-	element.entity = tomo.NewEntity(element)
+	element.entity = tomo.GetBackend().NewEntity(element)
 	element.construct()
 	return
 }
 
 type slider struct {
+	entity tomo.Entity
+
+	c tomo.Case
+
 	value      float64
 	vertical   bool
 	dragging   bool
@@ -43,9 +46,9 @@ type slider struct {
 func (element *slider) construct () {
 	element.enabled = true
 	if element.vertical {
-		element.theme.Case = tomo.C("tomo", "sliderVertical")
+		element.c = tomo.C("tomo", "sliderVertical")
 	} else {
-		element.theme.Case = tomo.C("tomo", "sliderHorizontal")
+		element.c = tomo.C("tomo", "sliderHorizontal")
 	}
 	element.updateMinimumSize()
 }
@@ -58,7 +61,7 @@ func (element *slider) Entity () tomo.Entity {
 // Draw causes the element to draw to the specified destination canvas.
 func (element *slider) Draw (destination artist.Canvas) {
 	bounds := element.entity.Bounds()
-	element.track = element.theme.Padding(tomo.PatternGutter).Apply(bounds)
+	element.track = element.entity.Theme().Padding(tomo.PatternGutter, element.c).Apply(bounds)
 	if element.vertical {
 		barSize := element.track.Dx()
 		element.bar = image.Rect(0, 0, barSize, barSize).Add(element.track.Min)
@@ -80,8 +83,8 @@ func (element *slider) Draw (destination artist.Canvas) {
 		Focused:  element.entity.Focused(),
 		Pressed:  element.dragging,
 	}
-	element.theme.Pattern(tomo.PatternGutter, state).Draw(destination, bounds)
-	element.theme.Pattern(tomo.PatternHandle, state).Draw(destination, element.bar)
+	element.entity.Theme().Pattern(tomo.PatternGutter, state, element.c).Draw(destination, bounds)
+	element.entity.Theme().Pattern(tomo.PatternHandle, state, element.c).Draw(destination, element.bar)
 }
 
 // Focus gives this element input focus.
@@ -205,21 +208,12 @@ func (element *slider) OnRelease (callback func ()) {
 	element.onRelease = callback
 }
 
-// SetTheme sets the element's theme.
-func (element *slider) SetTheme (new tomo.Theme) {
-	if new == element.theme.Theme { return }
-	element.theme.Theme = new
-	element.entity.Invalidate()
-}
-
-// SetConfig sets the element's configuration.
-func (element *slider) SetConfig (new tomo.Config) {
-	if new == element.config.Config { return }
-	element.config.Config = new
+func (element *slider) HandleThemeChange () {
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
 
+
 func (element *slider) changeValue (delta float64) {
 	element.value += delta
 	if element.value < 0 {
@@ -252,8 +246,8 @@ func (element *slider) valueFor (x, y int) (value float64) {
 }
 
 func (element *slider) updateMinimumSize () {
-	gutterPadding := element.theme.Padding(tomo.PatternGutter)
-	handlePadding := element.theme.Padding(tomo.PatternHandle)
+	gutterPadding := element.entity.Theme().Padding(tomo.PatternGutter, element.c)
+	handlePadding := element.entity.Theme().Padding(tomo.PatternHandle, element.c)
 	if element.vertical {
 		element.entity.SetMinimumSize (
 			gutterPadding.Horizontal() + handlePadding.Horizontal(),
diff --git a/elements/spacer.go b/elements/spacer.go
index 0f6d73d..1f072df 100644
--- a/elements/spacer.go
+++ b/elements/spacer.go
@@ -3,6 +3,8 @@ package elements
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
 
+var spacerCase = tomo.C("tomo", "spacer")
+
 // Spacer can be used to put space between two elements..
 type Spacer struct {
 	entity tomo.Entity
@@ -12,8 +14,7 @@ type Spacer struct {
 // NewSpacer creates a new spacer.
 func NewSpacer () (element *Spacer) {
 	element = &Spacer { }
-	element.entity = tomo.NewEntity(element).(spacerEntity)
-	element.theme.Case = tomo.C("tomo", "spacer")
+	element.entity = tomo.GetBackend().NewEntity(element)
 	element.updateMinimumSize()
 	return
 }
@@ -35,14 +36,14 @@ func (element *Spacer) Draw (destination artist.Canvas) {
 	bounds := element.entity.Bounds()
 
 	if element.line {
-		pattern := element.theme.Pattern (
+		pattern := element.entity.Theme().Pattern (
 			tomo.PatternLine,
-			tomo.State { })
+			tomo.State { }, spacerCase)
 		pattern.Draw(destination, bounds)
 	} else {
-		pattern := element.theme.Pattern (
+		pattern := element.entity.Theme().Pattern (
 			tomo.PatternBackground,
-			tomo.State { })
+			tomo.State { }, spacerCase)
 		pattern.Draw(destination, bounds)
 	}
 }
@@ -55,23 +56,13 @@ func (element *Spacer) SetLine (line bool) {
 	element.entity.Invalidate()
 }
 
-// SetTheme sets the element's theme.
-func (element *Spacer) SetTheme (new tomo.Theme) {
-	if new == element.theme.Theme { return }
-	element.theme.Theme = new
-	element.entity.Invalidate()
-}
-
-// SetConfig sets the element's configuration.
-func (element *Spacer) SetConfig (new tomo.Config) {
-	if new == element.config.Config { return }
-	element.config.Config = new
+func (element *Spacer) HandleThemeChange () {
 	element.entity.Invalidate()
 }
 
 func (element *Spacer) updateMinimumSize () {
 	if element.line {
-		padding := element.theme.Padding(tomo.PatternLine)
+		padding := element.entity.Theme().Padding(tomo.PatternLine, spacerCase)
 		element.entity.SetMinimumSize (
 			padding.Horizontal(),
 			padding.Vertical())
diff --git a/elements/switch.go b/elements/switch.go
index 11d139f..dd6ea85 100644
--- a/elements/switch.go
+++ b/elements/switch.go
@@ -6,6 +6,8 @@ import "git.tebibyte.media/sashakoshka/tomo/input"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
 import "git.tebibyte.media/sashakoshka/tomo/textdraw"
 
+var switchCase = tomo.C("tomo", "switch")
+
 // Switch is a toggle-able on/off switch with an optional label. It is
 // functionally identical to Checkbox, but plays a different semantic role.
 type Switch struct {
@@ -27,11 +29,10 @@ func NewSwitch (text string, on bool) (element *Switch) {
 		text:    text,
 		enabled: true,
 	}
-	element.entity = tomo.NewEntity(element).(checkboxEntity)
-	element.theme.Case = tomo.C("tomo", "switch")
-	element.drawer.SetFace (element.theme.FontFace (
+	element.entity = tomo.GetBackend().NewEntity(element)
+	element.drawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
+		tomo.FontSizeNormal, switchCase))
 	element.drawer.SetText([]rune(text))
 	element.updateMinimumSize()
 	return
@@ -71,24 +72,24 @@ func (element *Switch) Draw (destination artist.Canvas) {
 		}
 	}
 
-	gutterPattern := element.theme.Pattern (
-		tomo.PatternGutter, state)
+	gutterPattern := element.entity.Theme().Pattern (
+		tomo.PatternGutter, state, switchCase)
 	gutterPattern.Draw(destination, gutterBounds)
 	
-	handlePattern := element.theme.Pattern (
-		tomo.PatternHandle, state)
+	handlePattern := element.entity.Theme().Pattern (
+		tomo.PatternHandle, state, switchCase)
 	handlePattern.Draw(destination, handleBounds)
 
 	textBounds := element.drawer.LayoutBounds()
 	offset := bounds.Min.Add(image.Point {
 		X: bounds.Dy() * 2 +
-			element.theme.Margin(tomo.PatternBackground).X,
+			element.entity.Theme().Margin(tomo.PatternBackground, switchCase).X,
 	})
 
 	offset.Y -= textBounds.Min.Y
 	offset.X -= textBounds.Min.X
 
-	foreground := element.theme.Color(tomo.ColorForeground, state)
+	foreground := element.entity.Theme().Color(tomo.ColorForeground, state, switchCase)
 	element.drawer.Draw(destination, foreground, offset)
 }
 
@@ -181,21 +182,10 @@ func (element *Switch) SetText (text string) {
 	element.entity.Invalidate()
 }
 
-// SetTheme sets the element's theme.
-func (element *Switch) SetTheme (new tomo.Theme) {
-	if new == element.theme.Theme { return }
-	element.theme.Theme = new
-	element.drawer.SetFace (element.theme.FontFace (
+func (element *Switch) HandleThemeChange () {
+	element.drawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
-	element.updateMinimumSize()
-	element.entity.Invalidate()
-}
-
-// SetConfig sets the element's configuration.
-func (element *Switch) SetConfig (new tomo.Config) {
-	if new == element.config.Config { return }
-	element.config.Config = new
+		tomo.FontSizeNormal, switchCase))
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
@@ -209,7 +199,7 @@ func (element *Switch) updateMinimumSize () {
 	} else {
 		element.entity.SetMinimumSize (
 			lineHeight * 2 +
-			element.theme.Margin(tomo.PatternBackground).X +
+			element.entity.Theme().Margin(tomo.PatternBackground, switchCase).X +
 			textBounds.Dx(),
 			lineHeight)
 	}
diff --git a/elements/textbox.go b/elements/textbox.go
index fe1dfa3..81cc5e0 100644
--- a/elements/textbox.go
+++ b/elements/textbox.go
@@ -12,6 +12,8 @@ import "git.tebibyte.media/sashakoshka/tomo/textmanip"
 import "git.tebibyte.media/sashakoshka/tomo/fixedutil"
 import "git.tebibyte.media/sashakoshka/tomo/artist/shapes"
 
+var textBoxCase = tomo.C("tomo", "textBox")
+
 // TextBox is a single-line text input.
 type TextBox struct {
 	entity tomo.Entity
@@ -38,15 +40,14 @@ type TextBox struct {
 // text.
 func NewTextBox (placeholder, value string) (element *TextBox) {
 	element = &TextBox { enabled: true }
-	element.theme.Case = tomo.C("tomo", "textBox")
-	element.entity = tomo.NewEntity(element).(textBoxEntity)
+	element.entity = tomo.GetBackend().NewEntity(element)
 	element.placeholder = placeholder
-	element.placeholderDrawer.SetFace (element.theme.FontFace (
+	element.placeholderDrawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
-	element.valueDrawer.SetFace (element.theme.FontFace (
+		tomo.FontSizeNormal, textBoxCase))
+	element.valueDrawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
+		tomo.FontSizeNormal, textBoxCase))
 	element.placeholderDrawer.SetText([]rune(placeholder))
 	element.updateMinimumSize()
 	element.SetValue(value)
@@ -63,15 +64,15 @@ func (element *TextBox) Draw (destination artist.Canvas) {
 	bounds := element.entity.Bounds()
 
 	state := element.state()
-	pattern := element.theme.Pattern(tomo.PatternInput, state)
-	padding := element.theme.Padding(tomo.PatternInput)
-	innerCanvas := canvas.Cut(destination, padding.Apply(bounds))
+	pattern := element.entity.Theme().Pattern(tomo.PatternInput, state, textBoxCase)
+	padding := element.entity.Theme().Padding(tomo.PatternInput, textBoxCase)
+	innerCanvas := artist.Cut(destination, padding.Apply(bounds))
 	pattern.Draw(destination, bounds)
 	offset := element.textOffset()
 
 	if element.entity.Focused() && !element.dot.Empty() {
 		// draw selection bounds
-		accent := element.theme.Color(tomo.ColorAccent,  state)
+		accent := element.entity.Theme().Color(tomo.ColorAccent, state, textBoxCase)
 		canon := element.dot.Canon()
 		foff  := fixedutil.Pt(offset)
 		start := element.valueDrawer.PositionAt(canon.Start).Add(foff)
@@ -89,9 +90,9 @@ func (element *TextBox) Draw (destination artist.Canvas) {
 	if len(element.text) == 0 {
 		// draw placeholder
 		textBounds := element.placeholderDrawer.LayoutBounds()
-		foreground := element.theme.Color (
+		foreground := element.entity.Theme().Color (
 			tomo.ColorForeground,
-			tomo.State { Disabled: true })
+			tomo.State { Disabled: true }, textBoxCase)
 		element.placeholderDrawer.Draw (
 			innerCanvas,
 			foreground,
@@ -99,7 +100,7 @@ func (element *TextBox) Draw (destination artist.Canvas) {
 	} else {
 		// draw input value
 		textBounds := element.valueDrawer.LayoutBounds()
-		foreground := element.theme.Color(tomo.ColorForeground, state)
+		foreground := element.entity.Theme().Color(tomo.ColorForeground, state, textBoxCase)
 		element.valueDrawer.Draw (
 			innerCanvas,
 			foreground,
@@ -108,7 +109,7 @@ func (element *TextBox) Draw (destination artist.Canvas) {
 	
 	if element.entity.Focused() && element.dot.Empty() {
 		// draw cursor
-		foreground := element.theme.Color(tomo.ColorForeground, state)
+		foreground := element.entity.Theme().Color(tomo.ColorForeground, state, textBoxCase)
 		cursorPosition := fixedutil.RoundPt (
 			element.valueDrawer.PositionAt(element.dot.End))
 		shapes.ColorLine (
@@ -144,7 +145,7 @@ func (element *TextBox) HandleMouseDown  (
 		runeIndex := element.atPosition(position)
 		if runeIndex == -1 { return }
 		
-		if time.Since(element.lastClick) < element.config.DoubleClickDelay() {
+		if time.Since(element.lastClick) < element.entity.Config().DoubleClickDelay() {
 			element.dragging = 2
 			element.dot = textmanip.WordAround(element.text, runeIndex)
 		} else {
@@ -202,7 +203,7 @@ func (element *TextBox) HandleMotion (position image.Point) {
 }
 
 func (element *TextBox) textOffset () image.Point {
-	padding     := element.theme.Padding(tomo.PatternInput)
+	padding     := element.entity.Theme().Padding(tomo.PatternInput, textBoxCase)
 	bounds      := element.entity.Bounds()
 	innerBounds := padding.Apply(bounds)
 	textHeight  := element.valueDrawer.LineHeight().Round()
@@ -464,27 +465,17 @@ func (element *TextBox) ScrollAxes () (horizontal, vertical bool) {
 	return true, false
 }
 
-// SetTheme sets the element's theme.
-func (element *TextBox) SetTheme (new tomo.Theme) {
-	if new == element.theme.Theme { return }
-	element.theme.Theme = new
-	face := element.theme.FontFace (
+func (element *TextBox) HandleThemeChange () {
+	face := element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal)
+		tomo.FontSizeNormal,
+		textBoxCase)
 	element.placeholderDrawer.SetFace(face)
 	element.valueDrawer.SetFace(face)
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
 
-// SetConfig sets the element's configuration.
-func (element *TextBox) SetConfig (new tomo.Config) {
-	if new == element.config.Config { return }
-	element.config.Config = new
-	element.updateMinimumSize()
-	element.entity.Invalidate()
-}
-
 func (element *TextBox) contextMenu (position image.Point) {
 	window := element.entity.Window()
 	menu, err := window.NewMenu(image.Rectangle { position, position })
@@ -528,12 +519,12 @@ func (element *TextBox) runOnChange () {
 }
 
 func (element *TextBox) scrollViewportWidth () (width int) {
-	padding := element.theme.Padding(tomo.PatternInput)
+	padding := element.entity.Theme().Padding(tomo.PatternInput, textBoxCase)
 	return padding.Apply(element.entity.Bounds()).Dx()
 }
 
 func (element *TextBox) scrollToCursor () {
-	padding := element.theme.Padding(tomo.PatternInput)
+	padding := element.entity.Theme().Padding(tomo.PatternInput, textBoxCase)
 	bounds  := padding.Apply(element.entity.Bounds())
 	bounds = bounds.Sub(bounds.Min)
 	bounds.Max.X -= element.valueDrawer.Em().Round()
@@ -556,7 +547,7 @@ func (element *TextBox) scrollToCursor () {
 
 func (element *TextBox) updateMinimumSize () {
 	textBounds := element.placeholderDrawer.LayoutBounds()
-	padding := element.theme.Padding(tomo.PatternInput)
+	padding := element.entity.Theme().Padding(tomo.PatternInput, textBoxCase)
 	element.entity.SetMinimumSize (
 		padding.Horizontal() + textBounds.Dx(),
 		padding.Vertical()   +
diff --git a/elements/togglebutton.go b/elements/togglebutton.go
index 0187de7..55e0e1e 100644
--- a/elements/togglebutton.go
+++ b/elements/togglebutton.go
@@ -6,6 +6,8 @@ import "git.tebibyte.media/sashakoshka/tomo/input"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
 import "git.tebibyte.media/sashakoshka/tomo/textdraw"
 
+var toggleButtonCase = tomo.C("tomo", "toggleButton")
+
 // ToggleButton is a togglable button.
 type ToggleButton struct {
 	entity tomo.Entity
@@ -30,11 +32,11 @@ func NewToggleButton (text string, on bool) (element *ToggleButton) {
 		enabled:  true,
 		on:       on,
 	}
-	element.entity = tomo.NewEntity(element)
-	element.theme.Case = tomo.C("tomo", "toggleButton")
-	element.drawer.SetFace (element.theme.FontFace (
+	element.entity = tomo.GetBackend().NewEntity(element)
+	element.drawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
+		tomo.FontSizeNormal,
+		toggleButtonCase))
 	element.SetText(text)
 	return
 }
@@ -48,10 +50,10 @@ func (element *ToggleButton) Entity () tomo.Entity {
 func (element *ToggleButton) Draw (destination artist.Canvas) {
 	state   := element.state()
 	bounds  := element.entity.Bounds()
-	pattern := element.theme.Pattern(tomo.PatternButton, state)
+	pattern := element.entity.Theme().Pattern(tomo.PatternButton, state, toggleButtonCase)
 	
-	lampPattern := element.theme.Pattern(tomo.PatternLamp, state)
-	lampPadding := element.theme.Padding(tomo.PatternLamp).Horizontal()
+	lampPattern := element.entity.Theme().Pattern(tomo.PatternLamp, state, toggleButtonCase)
+	lampPadding := element.entity.Theme().Padding(tomo.PatternLamp, toggleButtonCase).Horizontal()
 	lampBounds  := bounds
 	lampBounds.Max.X = lampBounds.Min.X + lampPadding
 	bounds.Min.X += lampPadding
@@ -59,9 +61,9 @@ func (element *ToggleButton) Draw (destination artist.Canvas) {
 	pattern.Draw(destination, bounds)
 	lampPattern.Draw(destination, lampBounds)
 	
-	foreground := element.theme.Color(tomo.ColorForeground, state)
-	sink       := element.theme.Sink(tomo.PatternButton)
-	margin     := element.theme.Margin(tomo.PatternButton)
+	foreground := element.entity.Theme().Color(tomo.ColorForeground, state, toggleButtonCase)
+	sink       := element.entity.Theme().Sink(tomo.PatternButton, toggleButtonCase)
+	margin     := element.entity.Theme().Margin(tomo.PatternButton, toggleButtonCase)
 	
 	offset := image.Pt (
 		bounds.Dx() / 2,
@@ -76,7 +78,7 @@ func (element *ToggleButton) Draw (destination artist.Canvas) {
 	}
 
 	if element.hasIcon {
-		icon := element.theme.Icon(element.iconId, tomo.IconSizeSmall) 
+		icon := element.entity.Theme().Icon(element.iconId, tomo.IconSizeSmall, toggleButtonCase) 
 		if icon != nil {
 			iconBounds := icon.Bounds()
 			addedWidth := iconBounds.Dx()
@@ -166,21 +168,10 @@ func (element *ToggleButton) ShowText (showText bool) {
 	element.entity.Invalidate()
 }
 
-// SetTheme sets the element's theme.
-func (element *ToggleButton) SetTheme (new tomo.Theme) {
-	if new == element.theme.Theme { return }
-	element.theme.Theme = new
-	element.drawer.SetFace (element.theme.FontFace (
+func (element *ToggleButton) HandleThemeChange () {
+	element.drawer.SetFace (element.entity.Theme().FontFace (
 		tomo.FontStyleRegular,
-		tomo.FontSizeNormal))
-	element.updateMinimumSize()
-	element.entity.Invalidate()
-}
-
-// SetConfig sets the element's configuration.
-func (element *ToggleButton) SetConfig (new tomo.Config) {
-	if new == element.config.Config { return }
-	element.config.Config = new
+		tomo.FontSizeNormal, toggleButtonCase))
 	element.updateMinimumSize()
 	element.entity.Invalidate()
 }
@@ -239,15 +230,15 @@ func (element *ToggleButton) HandleKeyUp(key input.Key, modifiers input.Modifier
 }
 
 func (element *ToggleButton) updateMinimumSize () {
-	padding     := element.theme.Padding(tomo.PatternButton)
-	margin      := element.theme.Margin(tomo.PatternButton)
-	lampPadding := element.theme.Padding(tomo.PatternLamp)
+	padding     := element.entity.Theme().Padding(tomo.PatternButton, toggleButtonCase)
+	margin      := element.entity.Theme().Margin(tomo.PatternButton, toggleButtonCase)
+	lampPadding := element.entity.Theme().Padding(tomo.PatternLamp, toggleButtonCase)
 
 	textBounds  := element.drawer.LayoutBounds()
 	minimumSize := textBounds.Sub(textBounds.Min)
 	
 	if element.hasIcon {
-		icon := element.theme.Icon(element.iconId, tomo.IconSizeSmall) 
+		icon := element.entity.Theme().Icon(element.iconId, tomo.IconSizeSmall, toggleButtonCase) 
 		if icon != nil {
 			bounds := icon.Bounds()
 			if element.showText {
diff --git a/examples/vbox/main.go b/examples/vbox/main.go
index 3c6bfd9..d22a921 100644
--- a/examples/vbox/main.go
+++ b/examples/vbox/main.go
@@ -1,16 +1,19 @@
 package main
 
 import "git.tebibyte.media/sashakoshka/tomo"
+import "git.tebibyte.media/sashakoshka/tomo/nasin"
 import "git.tebibyte.media/sashakoshka/tomo/elements"
 import "git.tebibyte.media/sashakoshka/tomo/elements/testing"
-import _ "git.tebibyte.media/sashakoshka/tomo/backends/all"
 
 func main () {
-	tomo.Run(run)
+	nasin.Run(Application { })
 }
 
-func run () {
-	window, _ := tomo.NewWindow(tomo.Bounds(0, 0, 128, 128))
+type Application struct { }
+
+func (Application) Init () error {
+	window, err := nasin.NewWindow(tomo.Bounds(0, 0, 128, 128))
+	if err != nil { return err }
 	window.SetTitle("vertical stack")
 
 	container := elements.NewVBox(elements.SpaceBoth)
@@ -25,13 +28,15 @@ func run () {
 		container.Adopt(okButton)
 		okButton.Focus()
 	})
-	okButton.OnClick(tomo.Stop)
+	okButton.OnClick(nasin.Stop)
 
 	container.AdoptExpand(label)
 	container.Adopt(button, okButton)
 	window.Adopt(container)
 	
 	okButton.Focus()
-	window.OnClose(tomo.Stop)
+	window.OnClose(nasin.Stop)
 	window.Show()
+	
+	return nil
 }
diff --git a/plugins/x/x/entity.go b/plugins/x/x/entity.go
index 6d04c02..7718e57 100644
--- a/plugins/x/x/entity.go
+++ b/plugins/x/x/entity.go
@@ -6,6 +6,7 @@ import "git.tebibyte.media/sashakoshka/tomo/artist"
 import "git.tebibyte.media/sashakoshka/tomo/ability"
 
 type entity struct {
+	backend     *backend
 	window      *window
 	parent      *entity
 	children    []*entity
@@ -21,7 +22,7 @@ type entity struct {
 }
 
 func (backend *backend) NewEntity (owner tomo.Element) tomo.Entity {
-	entity := &entity { element: owner }
+	entity := &entity { element: owner, backend: backend }
 	entity.InvalidateLayout()
 	return entity
 }
@@ -162,7 +163,7 @@ func (entity *entity) DrawBackground (destination artist.Canvas) {
 	if entity.parent != nil {
 		entity.parent.element.(ability.Container).DrawBackground(destination)
 	} else if entity.window != nil {
-		entity.window.system.theme.Pattern (
+		entity.backend.theme.Pattern (
 			tomo.PatternBackground,
 			tomo.State { },
 			tomo.C("tomo", "window")).Draw (
@@ -292,11 +293,11 @@ func (entity *entity) NotifyScrollBoundsChange () {
 // ----------- ThemeableEntity ----------- //
 
 func (entity *entity) Theme () tomo.Theme {
-	return entity.window.theme
+	return entity.backend.theme
 }
 
 // ----------- ConfigurableEntity ----------- //
 
 func (entity *entity) Config () tomo.Config {
-	return entity.window.config
+	return entity.backend.config
 }
diff --git a/plugins/x/x/system.go b/plugins/x/x/system.go
index 6817aa5..4143774 100644
--- a/plugins/x/x/system.go
+++ b/plugins/x/x/system.go
@@ -1,11 +1,8 @@
 package x
 
 import "image"
-import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
 import "git.tebibyte.media/sashakoshka/tomo/ability"
-import defaultTheme  "git.tebibyte.media/sashakoshka/tomo/default/theme"
-import defaultConfig "git.tebibyte.media/sashakoshka/tomo/default/config"
 
 type entitySet map[*entity] struct { }
 
@@ -26,10 +23,7 @@ type system struct {
 	child   *entity
 	focused *entity
 	canvas  artist.BasicCanvas
-
-	theme  tomo.Theme
-	config tomo.Config
-
+	
 	invalidateIgnore bool
 	drawingInvalid   entitySet
 	anyLayoutInvalid bool
@@ -43,12 +37,7 @@ func (system *system) initialize () {
 	system.drawingInvalid = make(entitySet)
 }
 
-func (system *system) setTheme (theme tomo.Theme) {
-	if theme == nil {
-		system.theme = defaultTheme.Default { }
-	} else {
-		system.theme = theme
-	}
+func (system *system) handleThemeChange () {
 	system.propagate (func (entity *entity) bool {
 		if child, ok := system.child.element.(ability.Themeable); ok {
 			child.HandleThemeChange()
@@ -57,12 +46,7 @@ func (system *system) setTheme (theme tomo.Theme) {
 	})
 }
 
-func (system *system) setConfig (config tomo.Config) {
-	if config == nil {
-		system.config = defaultConfig.Default { }
-	} else {
-		system.config = config
-	}
+func (system *system) handleConfigChange () {
 	system.propagate (func (entity *entity) bool {
 		if child, ok := system.child.element.(ability.Configurable); ok {
 			child.HandleConfigChange()
diff --git a/plugins/x/x/window.go b/plugins/x/x/window.go
index 85b20a1..18cbbf9 100644
--- a/plugins/x/x/window.go
+++ b/plugins/x/x/window.go
@@ -120,9 +120,6 @@ func (backend *backend) newWindow (
 		Connect(backend.connection, window.xWindow.Id)
 	xevent.SelectionRequestFun(window.handleSelectionRequest).
 		Connect(backend.connection, window.xWindow.Id)
-
-	window.setTheme(backend.theme)
-	window.setConfig(backend.config)
 	
 	window.metrics.bounds = bounds
 	window.setMinimumSize(8, 8)
diff --git a/plugins/x/x/x.go b/plugins/x/x/x.go
index a063129..82a88be 100644
--- a/plugins/x/x/x.go
+++ b/plugins/x/x/x.go
@@ -1,6 +1,8 @@
 package x
 
 import "git.tebibyte.media/sashakoshka/tomo"
+import defaultTheme  "git.tebibyte.media/sashakoshka/tomo/default/theme"
+import defaultConfig "git.tebibyte.media/sashakoshka/tomo/default/config"
 
 import "github.com/jezek/xgbutil"
 import "github.com/jezek/xgb/xproto"
@@ -96,17 +98,26 @@ func (backend *backend) Do (callback func ()) {
 
 func (backend *backend) SetTheme (theme tomo.Theme) {
 	backend.assert()
-	backend.theme = theme
+	if theme == nil {
+		backend.theme = defaultTheme.Default { }
+	} else {
+		backend.theme = theme
+	}
 	for _, window := range backend.windows {
-		window.setTheme(theme)
+		window.handleThemeChange()
 	}
 }
 
 func (backend *backend) SetConfig (config tomo.Config) {
 	backend.assert()
+	if config == nil {
+		backend.config = defaultConfig.Default { }
+	} else {
+		backend.config = config
+	}
 	backend.config = config
 	for _, window := range backend.windows {
-		window.setConfig(config)
+		window.handleConfigChange()
 	}
 }