> The effect of this new patch is weird:
>
> Dragging the right and/or bottom edge now moves the "cutoff" (for lack
> of a better word) instead of resizing the frame. The frame internal
> border, the mode-line, etc, stay in place, and resizing like this can
> cover them partially or completely, making further dragging of the
> same edge impossible. After, the only way to show the internal border
> again is to drag the left or top border. Which will refresh the
> rendering of all the borders.
I understand only partially but probably we see the same. When I drag
the right internal border here it disappears. When I now drag the
bottom border, the right border reappears at its old position, making
the previous drag a noop, and the bottom border disappears. So in
practice I cannot move any border.