diff --git a/elements/basic/button.go b/elements/basic/button.go
index bb254de..06c7edd 100644
--- a/elements/basic/button.go
+++ b/elements/basic/button.go
@@ -14,10 +14,13 @@ type Button struct {
 	pressed  bool
 	enabled  bool
 	selected bool
-	onClick func ()
 
 	text   string
 	drawer artist.TextDrawer
+	
+	onClick func ()
+	onSelectionRequest func () (granted bool)
+	onSelectionMotionRequest func (tomo.SelectionDirection) (granted bool)
 }
 
 // NewButton creates a new button with the specified label text.
@@ -41,7 +44,7 @@ func (element *Button) HandleMouseDown (x, y int, button tomo.Button) {
 	element.pressed = true
 	if element.core.HasImage() {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -50,7 +53,7 @@ func (element *Button) HandleMouseUp (x, y int, button tomo.Button) {
 	element.pressed = false
 	if element.core.HasImage() {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 
 	within := image.Point { x, y }.
@@ -63,7 +66,7 @@ func (element *Button) HandleMouseUp (x, y int, button tomo.Button) {
 }
 
 func (element *Button) HandleMouseMove (x, y int) { }
-func (element *Button) HandleScroll (x, y int, deltaX, deltaY float64) { }
+func (element *Button) HandleMouseScroll (x, y int, deltaX, deltaY float64) { }
 
 func (element *Button) HandleKeyDown (
 	key tomo.Key,
@@ -75,7 +78,7 @@ func (element *Button) HandleKeyDown (
 		element.pressed = true
 		if element.core.HasImage() {
 			element.draw()
-			element.core.PushAll()
+			element.core.DamageAll()
 		}
 	}
 }
@@ -85,7 +88,7 @@ func (element *Button) HandleKeyUp(key tomo.Key, modifiers tomo.Modifiers) {
 		element.pressed = false
 		if element.core.HasImage() {
 			element.draw()
-			element.core.PushAll()
+			element.core.DamageAll()
 		}
 		if !element.enabled { return }
 		if element.onClick != nil {
@@ -100,7 +103,9 @@ func (element *Button) Selected () (selected bool) {
 
 func (element *Button) Select () {
 	if !element.enabled { return }
-	element.core.RequestSelection()
+	if element.onSelectionRequest != nil {
+		element.onSelectionRequest()
+	}
 }
 
 func (element *Button) HandleSelection (
@@ -117,7 +122,7 @@ func (element *Button) HandleSelection (
 	element.selected = true
 	if element.core.HasImage() {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 	return true
 }
@@ -126,10 +131,20 @@ func (element *Button) HandleDeselection () {
 	element.selected = false
 	if element.core.HasImage() {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
+func (element *Button) OnSelectionRequest (callback func () (granted bool)) {
+	element.onSelectionRequest = callback
+}
+
+func (element *Button) OnSelectionMotionRequest (
+	callback func (direction tomo.SelectionDirection) (granted bool),
+) {
+	element.onSelectionMotionRequest = callback
+}
+
 // OnClick sets the function to be called when the button is clicked.
 func (element *Button) OnClick (callback func ()) {
 	element.onClick = callback
@@ -141,7 +156,7 @@ func (element *Button) SetEnabled (enabled bool) {
 	element.enabled = enabled
 	if element.core.HasImage () {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -157,7 +172,7 @@ func (element *Button) SetText (text string) {
 		theme.Padding() * 2 + textBounds.Dy())
 	if element.core.HasImage () {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
diff --git a/elements/basic/checkbox.go b/elements/basic/checkbox.go
index 8c9422a..27f85d1 100644
--- a/elements/basic/checkbox.go
+++ b/elements/basic/checkbox.go
@@ -15,10 +15,13 @@ type Checkbox struct {
 	checked  bool
 	enabled  bool
 	selected bool
-	onClick func ()
 
 	text   string
 	drawer artist.TextDrawer
+	
+	onClick func ()
+	onSelectionRequest func () (granted bool)
+	onSelectionMotionRequest func (tomo.SelectionDirection) (granted bool)
 }
 
 // NewCheckbox creates a new cbeckbox with the specified label text.
@@ -41,7 +44,7 @@ func (element *Checkbox) HandleMouseDown (x, y int, button tomo.Button) {
 	element.pressed = true
 	if element.core.HasImage() {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -57,7 +60,7 @@ func (element *Checkbox) HandleMouseUp (x, y int, button tomo.Button) {
 	
 	if element.core.HasImage() {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 	if within && element.onClick != nil {
 		element.onClick()
@@ -76,7 +79,7 @@ func (element *Checkbox) HandleKeyDown (
 		element.pressed = true
 		if element.core.HasImage() {
 			element.draw()
-			element.core.PushAll()
+			element.core.DamageAll()
 		}
 	}
 }
@@ -87,7 +90,7 @@ func (element *Checkbox) HandleKeyUp (key tomo.Key, modifiers tomo.Modifiers) {
 		element.checked = !element.checked
 		if element.core.HasImage() {
 			element.draw()
-			element.core.PushAll()
+			element.core.DamageAll()
 		}
 		if element.onClick != nil {
 			element.onClick()
@@ -102,7 +105,10 @@ func (element *Checkbox) Selected () (selected bool) {
 
 // Select requests that this element be selected.
 func (element *Checkbox) Select () {
-	element.core.RequestSelection()
+	if !element.enabled { return }
+	if element.onSelectionRequest != nil {
+		element.onSelectionRequest()
+	}
 }
 
 func (element *Checkbox) HandleSelection (
@@ -119,7 +125,7 @@ func (element *Checkbox) HandleSelection (
 	element.selected = true
 	if element.core.HasImage() {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 	return true
 }
@@ -128,10 +134,20 @@ func (element *Checkbox) HandleDeselection () {
 	element.selected = false
 	if element.core.HasImage() {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
+func (element *Checkbox) OnSelectionRequest (callback func () (granted bool)) {
+	element.onSelectionRequest = callback
+}
+
+func (element *Checkbox) OnSelectionMotionRequest (
+	callback func (direction tomo.SelectionDirection) (granted bool),
+) {
+	element.onSelectionMotionRequest = callback
+}
+
 // OnClick sets the function to be called when the checkbox is toggled.
 func (element *Checkbox) OnClick (callback func ()) {
 	element.onClick = callback
@@ -148,7 +164,7 @@ func (element *Checkbox) SetEnabled (enabled bool) {
 	element.enabled = enabled
 	if element.core.HasImage () {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -164,7 +180,7 @@ func (element *Checkbox) SetText (text string) {
 		textBounds.Dy())
 	if element.core.HasImage () {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
diff --git a/elements/basic/container.go b/elements/basic/container.go
index 1e4e785..7770ba8 100644
--- a/elements/basic/container.go
+++ b/elements/basic/container.go
@@ -19,6 +19,10 @@ type Container struct {
 	selected   bool
 	selectable bool
 	flexible   bool
+	
+	onSelectionRequest func () (granted bool)
+	onSelectionMotionRequest func (tomo.SelectionDirection) (granted bool)
+	onFlexibleHeightChange func ()
 }
 
 // NewContainer creates a new container.
@@ -35,7 +39,7 @@ func (element *Container) SetLayout (layout tomo.Layout) {
 	if element.core.HasImage() {
 		element.recalculate()
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -43,38 +47,40 @@ func (element *Container) SetLayout (layout tomo.Layout) {
 // the element will expand (instead of contract to its minimum size), in
 // whatever way is defined by the current layout.
 func (element *Container) Adopt (child tomo.Element, expand bool) {
-	child.SetParentHooks (tomo.ParentHooks {
-		Draw: func (region tomo.Canvas) {
-			element.drawChildRegion(child, region)
-		},
-		MinimumSizeChange: func (int, int) {
-			element.updateMinimumSize()
-		},
-		FlexibleHeightChange: element.updateMinimumSize,
-		SelectionRequest: func () (granted bool) {
-			child, selectable := child.(tomo.Selectable)
-			if !selectable { return }
-			return element.childSelectionRequestCallback(child)
-		},
-		SelectionMotionRequest: func (
-			direction tomo.SelectionDirection,
-		) (
-			granted bool,
-		) {
-			return element.core.RequestSelectionMotion(direction)
-		},
+	// set event handlers
+	child.OnDamage (func (region tomo.Canvas) {
+		element.drawChildRegion(child, region)
 	})
+	child.OnMinimumSizeChange(element.updateMinimumSize)
+	if child0, ok := child.(tomo.Flexible); ok {
+		child0.OnFlexibleHeightChange(element.updateMinimumSize)
+	}
+	if child0, ok := child.(tomo.Selectable); ok {
+		child0.OnSelectionRequest (func () (granted bool) {
+			return element.childSelectionRequestCallback(child0)
+		})
+	}
+	if child0, ok := child.(tomo.Selectable); ok {
+		child0.OnSelectionMotionRequest (
+			func (direction tomo.SelectionDirection) (granted bool) {
+				if element.onSelectionMotionRequest == nil { return }
+				return element.onSelectionMotionRequest(direction)
+			})
+	}
+
+	// add child
 	element.children = append (element.children, tomo.LayoutEntry {
 		Element: child,
 		Expand:  expand,
 	})
 
+	// refresh stale data
 	element.updateMinimumSize()
 	element.reflectChildProperties()
 	if element.core.HasImage() && !element.warping {
 		element.recalculate()
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -97,7 +103,7 @@ func (element *Container) Warp (callback func ()) {
 	if element.core.HasImage() {
 		element.recalculate()
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -106,7 +112,7 @@ func (element *Container) Warp (callback func ()) {
 func (element *Container) Disown (child tomo.Element) {
 	for index, entry := range element.children {
 		if entry.Element == child {
-			entry.SetParentHooks(tomo.ParentHooks { })
+			element.clearChildEventHandlers(entry.Element)
 			element.children = append (
 				element.children[:index],
 				element.children[index + 1:]...)
@@ -119,7 +125,22 @@ func (element *Container) Disown (child tomo.Element) {
 	if element.core.HasImage() && !element.warping {
 		element.recalculate()
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
+	}
+}
+
+func (element *Container) clearChildEventHandlers (child tomo.Element) {
+	child.OnDamage(nil)
+	child.OnMinimumSizeChange(nil)
+	if child0, ok := child.(tomo.Selectable); ok {
+		child0.OnSelectionRequest(nil)
+		child0.OnSelectionMotionRequest(nil)
+		if child0.Selected() {
+			child0.HandleDeselection()
+		}
+	}
+	if child0, ok := child.(tomo.Flexible); ok {
+		child0.OnFlexibleHeightChange(nil)
 	}
 }
 
@@ -132,7 +153,7 @@ func (element *Container) DisownAll () {
 	if element.core.HasImage() && !element.warping {
 		element.recalculate()
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -213,7 +234,7 @@ func (element *Container) HandleScroll (x, y int, deltaX, deltaY float64) {
 	child, handlesMouse := element.ChildAt(image.Pt(x, y)).(tomo.MouseTarget)
 	if !handlesMouse { return }
 	childPosition := element.childPosition(child)
-	child.HandleScroll(x - childPosition.X, y - childPosition.Y, deltaX, deltaY)
+	child.HandleMouseScroll(x - childPosition.X, y - childPosition.Y, deltaX, deltaY)
 }
 
 func (element *Container) HandleKeyDown (
@@ -245,7 +266,9 @@ func (element *Container) Selected () (selected bool) {
 }
 
 func (element *Container) Select () {
-	element.core.RequestSelection()
+	if element.onSelectionRequest != nil {
+		element.onSelectionRequest()
+	}
 }
 
 func (element *Container) HandleSelection (direction tomo.SelectionDirection) (ok bool) {
@@ -300,10 +323,14 @@ func (element *Container) HandleSelection (direction tomo.SelectionDirection) (o
 	return false
 }
 
-func (element *Container) MinimumHeightFor (width int) (height int) {
+func (element *Container) FlexibleHeightFor (width int) (height int) {
 	return element.layout.MinimumHeightFor(element.children, width)
 }
 
+func (element *Container) OnFlexibleHeightChange (callback func ()) {
+	element.onFlexibleHeightChange = callback
+}
+
 func (element *Container) HandleDeselection () {
 	element.selected = false
 	element.forSelected (func (child tomo.Selectable) bool {
@@ -312,6 +339,16 @@ func (element *Container) HandleDeselection () {
 	})
 }
 
+func (element *Container) OnSelectionRequest (callback func () (granted bool)) {
+	element.onSelectionRequest = callback
+}
+
+func (element *Container) OnSelectionMotionRequest (
+	callback func (direction tomo.SelectionDirection) (granted bool),
+) {
+	element.onSelectionMotionRequest = callback
+}
+
 func (element *Container) forSelected (callback func (child tomo.Selectable) bool) {
 	for _, entry := range element.children {
 		child, selectable := entry.Element.(tomo.Selectable)
@@ -379,7 +416,7 @@ func (element *Container) childSelectionRequestCallback (
 ) (
 	granted bool,
 ) {
-	if element.core.RequestSelection() {
+	if element.onSelectionRequest != nil && element.onSelectionRequest() {
 		element.forSelected (func (child tomo.Selectable) bool {
 			child.HandleDeselection()
 			return true
@@ -422,7 +459,7 @@ func (element *Container) drawChildRegion (child tomo.Element, region tomo.Canva
 	for _, entry := range element.children {
 		if entry.Element == child {
 			artist.Paste(element.core, region, entry.Position)
-			element.core.PushRegion (
+			element.core.DamageRegion (
 				region.Bounds().Add(entry.Position))
 			break
 		}
diff --git a/elements/basic/label.go b/elements/basic/label.go
index 65ce585..7c2e2f0 100644
--- a/elements/basic/label.go
+++ b/elements/basic/label.go
@@ -13,6 +13,8 @@ type Label struct {
 	wrap   bool
 	text   string
 	drawer artist.TextDrawer
+	
+	onFlexibleHeightChange func ()
 }
 
 // NewLabel creates a new label. If wrap is set to true, the text inside will be
@@ -38,9 +40,9 @@ func (element *Label) Resize (width, height int) {
 	return
 }
 
-// MinimumHeightFor returns the reccomended height for this element based on the
-// given width in order to allow the text to wrap properly.
-func (element *Label) MinimumHeightFor (width int) (height int) {
+// FlexibleHeightFor returns the reccomended height for this element based on
+// the given width in order to allow the text to wrap properly.
+func (element *Label) FlexibleHeightFor (width int) (height int) {
 	if element.wrap {
 		return element.drawer.ReccomendedHeightFor(width)
 	} else {
@@ -49,6 +51,12 @@ func (element *Label) MinimumHeightFor (width int) (height int) {
 	}
 }
 
+// OnFlexibleHeightChange sets a function to be called when the parameters
+// affecting this element's flexible height are changed.
+func (element *Label) OnFlexibleHeightChange (callback func ()) {
+	element.onFlexibleHeightChange = callback
+}
+
 // SetText sets the label's text.
 func (element *Label) SetText (text string) {
 	if element.text == text { return }
@@ -59,7 +67,7 @@ func (element *Label) SetText (text string) {
 	
 	if element.core.HasImage () {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -78,7 +86,7 @@ func (element *Label) SetWrap (wrap bool) {
 	
 	if element.core.HasImage () {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -88,7 +96,9 @@ func (element *Label) updateMinimumSize () {
 		if em < 1 { em = theme.Padding() }
 		element.core.SetMinimumSize (
 			em, element.drawer.LineHeight().Round())
-		element.core.NotifyFlexibleHeightChange()
+		if element.onFlexibleHeightChange != nil {
+			element.onFlexibleHeightChange()
+		}
 	} else {
 		bounds := element.drawer.LayoutBounds()
 		element.core.SetMinimumSize(bounds.Dx(), bounds.Dy())
diff --git a/elements/basic/progressbar.go b/elements/basic/progressbar.go
index 6ac9778..4bef1b0 100644
--- a/elements/basic/progressbar.go
+++ b/elements/basic/progressbar.go
@@ -34,7 +34,7 @@ func (element *ProgressBar) SetProgress (progress float64) {
 	element.progress = progress
 	if element.core.HasImage() {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
diff --git a/elements/basic/scrollcontainer.go b/elements/basic/scrollcontainer.go
index a48adab..b3c8b81 100644
--- a/elements/basic/scrollcontainer.go
+++ b/elements/basic/scrollcontainer.go
@@ -23,6 +23,8 @@ type ScrollContainer struct {
 		enabled bool
 		bounds image.Rectangle
 	}
+
+	// TODO event handlers
 }
 
 // NewScrollContainer creates a new scroll container with the specified scroll
@@ -52,23 +54,18 @@ func (element *ScrollContainer) Resize (width, height int) {
 func (element *ScrollContainer) Adopt (child tomo.Scrollable) {
 	// disown previous child if it exists
 	if element.child != nil {
-		element.child.SetParentHooks (tomo.ParentHooks { })
-		if previousChild, ok := element.child.(tomo.Selectable); ok {
-			if previousChild.Selected() {
-				previousChild.HandleDeselection()
-			}
-		}
+		element.clearChildEventHandlers(child)
 	}
 
 	// adopt new child
 	element.child = child
 	if child != nil {
-		child.SetParentHooks (tomo.ParentHooks {
+		// child.SetParentHooks (tomo.ParentHooks {
 			// Draw: window.childDrawCallback,
 			// MinimumSizeChange: window.childMinimumSizeChangeCallback,
 			// FlexibleHeightChange: window.resizeChildToFit,
 			// SelectionRequest: window.childSelectionRequestCallback,
-		})
+		// })
 
 		// TODO: somehow inform the core that we do not in fact want to
 		// redraw the element.
@@ -84,6 +81,21 @@ func (element *ScrollContainer) Adopt (child tomo.Scrollable) {
 	}
 }
 
+func (element *ScrollContainer) clearChildEventHandlers (child tomo.Element) {
+	child.OnDamage(nil)
+	child.OnMinimumSizeChange(nil)
+	if child0, ok := child.(tomo.Selectable); ok {
+		child0.OnSelectionRequest(nil)
+		child0.OnSelectionMotionRequest(nil)
+		if child0.Selected() {
+			child0.HandleDeselection()
+		}
+	}
+	if child0, ok := child.(tomo.Flexible); ok {
+		child0.OnFlexibleHeightChange(nil)
+	}
+}
+
 func (element *ScrollContainer) recalculate () {
 	horizontal := &element.horizontal
 	vertical   := &element.vertical
diff --git a/elements/basic/spacer.go b/elements/basic/spacer.go
index 8456088..7cf7844 100644
--- a/elements/basic/spacer.go
+++ b/elements/basic/spacer.go
@@ -34,7 +34,7 @@ func (element *Spacer) SetLine (line bool) {
 	element.line = line
 	if element.core.HasImage() {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
diff --git a/elements/basic/textbox.go b/elements/basic/textbox.go
index 722dc76..7ba4d0f 100644
--- a/elements/basic/textbox.go
+++ b/elements/basic/textbox.go
@@ -25,6 +25,9 @@ type TextBox struct {
 	
 	onKeyDown func (tomo.Key, tomo.Modifiers, bool) (bool)
 	onChange  func ()
+	onSelectionRequest func () (granted bool)
+	onSelectionMotionRequest func (tomo.SelectionDirection) (granted bool)
+	onScrollBoundsChange func ()
 }
 
 // NewTextBox creates a new text box with the specified placeholder text, and
@@ -119,7 +122,7 @@ func (element *TextBox) HandleKeyDown (
 	
 	if altered && element.core.HasImage () {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -130,7 +133,9 @@ func (element *TextBox) Selected () (selected bool) {
 }
 
 func (element *TextBox) Select () {
-	element.core.RequestSelection()
+	if element.onSelectionRequest != nil {
+		element.onSelectionRequest()
+	}
 }
 
 func (element *TextBox) HandleSelection (
@@ -147,7 +152,7 @@ func (element *TextBox) HandleSelection (
 	element.selected = true
 	if element.core.HasImage() {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 	return true
 }
@@ -156,16 +161,26 @@ func (element *TextBox) HandleDeselection () {
 	element.selected = false
 	if element.core.HasImage() {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
+func (element *TextBox) OnSelectionRequest (callback func () (granted bool)) {
+	element.onSelectionRequest = callback
+}
+
+func (element *TextBox) OnSelectionMotionRequest (
+	callback func (direction tomo.SelectionDirection) (granted bool),
+) {
+	element.onSelectionMotionRequest = callback
+}
+
 func (element *TextBox) SetEnabled (enabled bool) {
 	if element.enabled == enabled { return }
 	element.enabled = enabled
 	if element.core.HasImage () {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -178,7 +193,7 @@ func (element *TextBox) SetPlaceholder (placeholder string) {
 	element.updateMinimumSize()
 	if element.core.HasImage () {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -195,7 +210,7 @@ func (element *TextBox) SetValue (text string) {
 	
 	if element.core.HasImage () {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
 	}
 }
 
@@ -246,9 +261,11 @@ func (element *TextBox) ScrollTo (position image.Point) {
 
 	if element.core.HasImage () {
 		element.draw()
-		element.core.PushAll()
+		element.core.DamageAll()
+	}
+	if element.onScrollBoundsChange != nil {
+		element.onScrollBoundsChange()
 	}
-	element.core.NotifyContentBoundsChange()
 }
 
 // ScrollAxes returns the supported axes for scrolling.
@@ -286,7 +303,9 @@ func (element *TextBox) scrollToCursor () {
 		element.scroll -= minX - cursorPosition.X
 		if element.scroll < 0 { element.scroll = 0 }
 	}
-	element.core.NotifyContentBoundsChange()
+	if element.onScrollBoundsChange != nil {
+		element.onScrollBoundsChange()
+	}
 }
 
 func (element *TextBox) draw () {