As the bottom-most window is shrunk to minimum, and the visible text
shrinks, suddenly the text displayed

is from some other remote location.   The visible text should not jump to
somewhere else.  Emacs 21.2 works

correctly, 22.3 and 23.1 have this problem. 

 

Start Emacs 23.1 (no .emacs file required)

Open a C++ .H file (mine has templated classes in it)

 

Split the windows, position the mark in the upper window on the 1st line,
position the mark in the lower window

on the last line:

 

    C-x 2 (split-window-vertically)

   In bottom window:

   M-> (end-of-buffer)

 

With the left mouse down, drag the divider downwards until the lower window
is minimum, then CONTINUE

to drag INTO the lower window without releasing the left mouse.

 

The instant the mouse enters the lower window, observe the visible text
jumps to the 1st line.

 

The visible text should remain at end-of-buffer.