Bug 142459 Shift+click on scroll bar should jump to that location r=varga sr=bryner a=asa

layout/xul/base/src/nsSliderFrame.cpp

@@ -628,7 +628,8 @@ nsSliderFrame::HandleEvent(nsIPresContext* aPresContext,
     //return nsFrame::HandleEvent(aPresContext, aEvent, aEventStatus);
     return NS_OK;
   }
-  else if (mMiddlePref && aEvent->message == NS_MOUSE_MIDDLE_BUTTON_DOWN) {
+  else if ((aEvent->message == NS_MOUSE_LEFT_BUTTON_DOWN && ((nsMouseEvent *)aEvent)->isShift)
+      || (mMiddlePref && aEvent->message == NS_MOUSE_MIDDLE_BUTTON_DOWN)) {
     // convert coord from twips to pixels
     nscoord pos = isHorizontal ? aEvent->point.x : aEvent->point.y;
     float p2t;
@@ -924,14 +925,18 @@ nsSliderFrame::MouseDown(nsIDOMEvent* aMouseEvent)
   nsCOMPtr<nsIDOMMouseEvent> mouseEvent(do_QueryInterface(aMouseEvent));
 
   PRUint16 button = 0;
+  PRBool scrollToClick = PR_FALSE;
+  mouseEvent->GetShiftKey(&scrollToClick);
   mouseEvent->GetButton(&button);
-  if((mMiddlePref && button != 0 && button != 1) ||
-     (!mMiddlePref && button != 0))
+  if (button != 0) {
+    if (button != 1 || !mMiddlePref)
       return NS_OK;
+    scrollToClick = PR_TRUE;
+  }
 
-  // If middle button, first place the middle of the slider thumb
-  // under the click
-  if (button == 1) {
+  // If shift click or middle button, first
+  // place the middle of the slider thumb under the click
+  if (scrollToClick) {
 
     nscoord pos;
     nscoord pospx;
@@ -1092,6 +1097,9 @@ nsSliderFrame::HandlePress(nsIPresContext* aPresContext,
                            nsGUIEvent*     aEvent,
                            nsEventStatus*  aEventStatus)
 {
+  if (((nsMouseEvent *)aEvent)->isShift)
+    return NS_OK;
+
   nsIFrame* thumbFrame = mFrames.FirstChild();
   if (!thumbFrame) // display:none?
     return NS_OK;