If I display two buffers side-by-side and scrolled the window up and
down using the scrolling wheel of a mouse, most of the time only the
right hand side window will take effect even I select the left hand
side window by putting the cursor at the left side window. Sometimes
the problem disappear if I quit the editor and started it again,
however, this solution didn't always work.
I have some code I wrote to handle the scroll wheel. It scrolls the
window that the mouse is in, but does not select the window. You can
find it at
http://xemacs.seanm.ca/ under intellimouse.
Cheers,
Sean MacLennan