Scrollbar and ScrollContainer use ScrollTo correctly

scrollbar.go

@@ -98,9 +98,9 @@ func (this *Scrollbar) SetValue (value float64) {
 	position    := trackLength * value
 	point       := this.layout.linked.ContentBounds().Min
 	if this.layout.vertical {
-		point.Y = int(position)
+		point.Y = -int(position)
 	} else {
-		point.X = int(position)
+		point.X = -int(position)
 	}
 	this.layout.linked.ScrollTo(point)
 	
@@ -173,15 +173,15 @@ func (this *Scrollbar) handleMouseDown (button input.Button) {
 		}
 	case input.ButtonMiddle:
 		if above {
-			this.scrollBy(-this.pageSize())
-		} else {
 			this.scrollBy(this.pageSize())
+		} else {
+			this.scrollBy(-this.pageSize())
 		}
 	case input.ButtonRight:
 		if above {
-			this.scrollBy(-this.stepSize())
-		} else {
 			this.scrollBy(this.stepSize())
+		} else {
+			this.scrollBy(-this.stepSize())
 		}
 	}
 }
@@ -200,7 +200,7 @@ func (this *Scrollbar) handleScroll (x, y float64) {
 	if this.layout.linked == nil { return }
 	this.layout.linked.ScrollTo (
 		this.layout.linked.ContentBounds().Min.
-		Add(image.Pt(int(x), int(y))))
+		Sub(image.Pt(int(x), int(y))))
 }
 
 func (this *Scrollbar) drag () {
@@ -327,7 +327,7 @@ func (this scrollbarLayout) Arrange (hints tomo.LayoutHints, boxes []tomo.Box) {
 	} else {
 		handleOffset = image.Pt(int(handlePosition), 0)
 	}
-	handle = handle.Add(handleOffset).Add(gutter.Min)
+	handle = handle.Sub(handleOffset).Add(gutter.Min)
 	
 	// place handle
 	boxes[0].SetBounds(handle)

scrollcontainer.go

@@ -108,7 +108,7 @@ func (this *ScrollContainer) handleScroll (x, y float64) {
 	if this.layout.root == nil { return }
 	this.layout.root.ScrollTo (
 		this.layout.root.ContentBounds().Min.
-		Add(image.Pt(int(x), int(y))))
+		Sub(image.Pt(int(x), int(y))))
 }
 
 type scrollContainerLayout struct {