Fixed transparent boxes not redrawing sometimes

containerbox.go

@@ -1,6 +1,7 @@
 package x
 
 import "image"
+import "image/color"
 import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/tomo/event"
 import "git.tebibyte.media/tomo/tomo/canvas"
@@ -29,6 +30,16 @@ func (backend *Backend) NewContainerBox() tomo.ContainerBox {
 	return this
 }
 
+func (this *containerBox) SetColor (c color.Color) {
+	this.box.SetColor(c)
+	this.invalidateTransparentChildren()
+}
+
+func (this *containerBox) SetTexture (texture canvas.Texture) {
+	this.box.SetTexture(texture)
+	this.invalidateTransparentChildren()
+}
+
 func (this *containerBox) SetOverflow (horizontal, vertical bool) {
 	if this.hOverflow == horizontal && this.vOverflow == vertical { return }
 	this.hOverflow = horizontal
@@ -162,6 +173,17 @@ func (this *containerBox) drawBackgroundPart (can canvas.Canvas) {
 	pen.Rectangle(this.innerClippingBounds)
 }
 
+func (this *containerBox) invalidateTransparentChildren () {
+	window := this.window()
+	if this.window == nil { return }
+	for _, box := range this.children {
+		box := assertAnyBox(box)
+		if box.transparent() {
+			window.invalidateDraw(box)
+		}
+	}
+}
+
 func (this *containerBox) flushActionQueue () {
 	for _, box := range this.children {
 		box.(anyBox).flushActionQueue()

system.go

@@ -52,6 +52,7 @@ type anyBox interface {
 	recursiveRedo    ()
 	canBeFocused     () bool
 	boxUnder         (image.Point) anyBox
+	transparent      () bool
 
 	propagate    (func (anyBox) bool) bool
 	propagateAlt (func (anyBox) bool) bool