diff --git a/scrollbar.go b/scrollbar.go
index 4f4f5da..3f2b707 100644
--- a/scrollbar.go
+++ b/scrollbar.go
@@ -60,9 +60,9 @@ func NewHorizontalScrollbar () *Scrollbar {
 	return newScrollbar("horizontal")
 }
 
-// Link assigns this scrollbar to a ContentBox. Closing the returned cookie will
-// unlink it.
-func (this *Scrollbar) Link (box tomo.ContentBox) event.Cookie {
+// Link assigns this scrollbar to a ContentObject. Closing the returned cookie
+// will unlink it.
+func (this *Scrollbar) Link (box tomo.ContentObject) event.Cookie {
 	this.layout.linked = box
 	this.linkCookie = this.newLinkCookie (
 		box.OnContentBoundsChange(this.handleLinkedContentBoundsChange))
@@ -230,7 +230,7 @@ func (this *Scrollbar) fallbackDragOffset () image.Point {
 
 func (this *Scrollbar) pageSize () int {
 	if this.layout.linked == nil { return 0 }
-	viewport := this.layout.linked.InnerBounds()
+	viewport := this.layout.linked.GetBox().InnerBounds()
 	if this.layout.vertical {
 		return viewport.Dy()
 	} else {
@@ -279,7 +279,7 @@ func (this *scrollbarCookie) Close () {
 type scrollbarLayout struct {
 	vertical bool
 	value    float64
-	linked   tomo.ContentBox
+	linked   tomo.ContentObject
 }
 
 func (scrollbarLayout) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
@@ -341,9 +341,9 @@ func (this scrollbarLayout) viewportContentRatio () float64 {
 
 func (this scrollbarLayout) viewportLength () float64 {
 	if this.vertical {
-		return float64(this.linked.InnerBounds().Dy())
+		return float64(this.linked.GetBox().InnerBounds().Dy())
 	} else {
-		return float64(this.linked.InnerBounds().Dx())
+		return float64(this.linked.GetBox().InnerBounds().Dx())
 	}
 }
 
diff --git a/scrollcontainer.go b/scrollcontainer.go
index 927446f..efd96ec 100644
--- a/scrollcontainer.go
+++ b/scrollcontainer.go
@@ -68,7 +68,7 @@ func NewScrollContainer (sides ScrollSide) *ScrollContainer {
 // SetRoot sets the root child of the ScrollContainer. There can only be one at
 // a time, and setting it will remove and unlink the current child if there is
 // one.
-func (this *ScrollContainer) SetRoot (root tomo.ContentBox) {
+func (this *ScrollContainer) SetRoot (root tomo.ContentObject) {
 	if this.layout.root != nil {
 		// remove root and close cookies
 		this.Remove(this.layout.root)
@@ -134,14 +134,14 @@ func (this *ScrollContainer) handleScroll (x, y float64) {
 }
 
 type scrollContainerLayout struct {
-	root       tomo.ContentBox
+	root       tomo.ContentObject
 	horizontal *Scrollbar
 	vertical   *Scrollbar
 }
 
 func (this *scrollContainerLayout) MinimumSize (hints tomo.LayoutHints, boxes []tomo.Box) image.Point {
 	var minimum image.Point; if this.root != nil {
-		minimum = this.root.MinimumSize()
+		minimum = this.root.GetBox().MinimumSize()
 	}
 	if this.horizontal != nil {
 		minimum.Y += this.horizontal.MinimumSize().Y
@@ -165,7 +165,7 @@ func (this *scrollContainerLayout) Arrange (hints tomo.LayoutHints, boxes []tomo
 		rootBounds.Max.X -= this.vertical.MinimumSize().X
 	}
 	if this.root != nil {
-		this.root.SetBounds(rootBounds)
+		this.root.GetBox().SetBounds(rootBounds)
 	}
 	if this.horizontal != nil {
 		this.horizontal.SetBounds(image.Rect (