Update Tomo API

scrollbar.go

@@ -306,9 +306,10 @@ func (this scrollbarLayout) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
 	handleLength := gutterLength * this.viewportContentRatio()
 	if handleLength < handleMin { handleLength = handleMin }
 	if handleLength >= gutterLength {
-		// just hide the handle if it isn't needed.
-		// TODO: we need a way to hide and show boxes, this is janky as
-		// fuck
+		// just hide the handle if it isn't needed. we are the layout
+		// and we shouldn't be adding and removing boxes, so this is
+		// really the only good way to hide things.
+		// TODO perhaps have a "Hidden" rectangle in the Tomo API?
 		boxes[0].SetBounds(image.Rect(-16, -16, 0, 0))
 		return
 	}