Make contents of combobox follow the finger when scrolling with a pan gesture

It is the contents that we are dragging with the gesture, not the
scrollbar "thumb". The DoScroll() call takes as argument how much the
"thumb" should be moved, though.

Change-Id: Id95a4bf9d2bb4e950dd85c6bebb4d2b5f2726ee0

vcl/source/window/window2.cxx

@@ -760,7 +760,7 @@ bool Window::HandleScrollCommand( const CommandEvent& rCmd,
                 else if(pData->meEventType == GestureEventType::PanningUpdate)
                 {
                     long nOriginalPosition = mpWindowImpl->mpFrameData->mnTouchPanPosition;
-                    pVScrl->DoScroll(nOriginalPosition + (pData->mfOffset));
+                    pVScrl->DoScroll(nOriginalPosition + (pData->mfOffset / pVScrl->GetVisibleSize()));
                 }
                 if (pData->meEventType == GestureEventType::PanningEnd)
                 {