BUG ID: Bugzilla bug 4840 Frames only resize wider, can't make them narrower
STEPS TO TEST: Drag the vertical split bar below to the left and release it.
TEST PASS: The frames will resize accordingly, with the split bar where you released it.
TEST FAIL: The split bar will not follow the mouse when dragged to the left. After releasing the mouse button, the frames will not resize and the split bar will continue to follow the mouse.