Bug 1121335 - Choose the right selection range for drag mode, r=roc

layout/base/SelectionCarets.cpp

@@ -771,8 +771,10 @@ SelectionCarets::DragSelection(const nsPoint &movePoint)
     return nsEventStatus_eConsumeNoDefault;
   }
 
+  // Limit the drag behavior not to cross the end of last selection range
+  // when drag the start frame and vice versa
   nsRefPtr<nsRange> range = mDragMode == START_FRAME ?
-    selection->GetRangeAt(0) : selection->GetRangeAt(rangeCount - 1);
+    selection->GetRangeAt(rangeCount - 1) : selection->GetRangeAt(0);
   if (!CompareRangeWithContentOffset(range, fs, offsets, mDragMode)) {
     return nsEventStatus_eConsumeNoDefault;
   }