Bug in window resizing?

[Lennart Borgman]

While trying to finish a new version of balance-windows I discovered 
what seems to be a bug: When I try to resize a window by dragging the 
lower border the upper border of this window is instead moved.

This looks very weird and unexpected so I would be glad for confirmation 
of the behaviour by others. Do the following:

 emacs -Q
 C-x 2, C-x 3, C-x 2

You should then arrive at a window geometry something like this (view 
with fixed char width):

+-------------+-----------+
|             |           |
+-moves down--+           +
|             |           |
+---drag up---+-----------+
|                         |
|                         |
|                         |
+-------------------------+

The strange thing is that when I try to drag the border marked with 
"drag up" this border does not move, but the border above moves down. 
(It seems like this does not only happen while dragging, but this is the 
most easy way to demonstrate it.)

This happens to me on w32 with CVS Emacs built 2005-09-03. I have 
applied some patches to the C sources, but none that I would believe 
could influence this.