Scrollbars accept both directions of scroll

scrollbar.go

@@ -235,6 +235,16 @@ func (this *Scrollbar) handleMouseMove () bool {
 
 func (this *Scrollbar) handleScroll (x, y float64) bool {
 	if this.layout.linked == nil { return false }
+	
+	delta := (x + y)
+	if this.layout.vertical {
+		x = 0
+		y = delta
+	} else {
+		x = delta
+		y = 0
+	}
+	
 	this.layout.linked.ScrollTo (
 		this.layout.linked.ContentBounds().Min.
 		Sub(image.Pt(int(x), int(y))))