bug#2996: 23.0.92; Scrolling narrows region

[martin rudalics <rudalics@gmx.at>]

 > Here's the recipe:
 >
 > 1. emacs -Q
 >
 > 2. C-x C-f file
 >    file should contain more than a screenfull of text.
 >
 > 3. Right-click somewhere in the window to produce an active region. If
 >    you didn't move point before this, the region starts at the very top
 >    of the buffer.
 >
 > 4. Right-click somewhere further down to see, that the region is
 >    resized.
 >
 > 5. Scroll down using the mousewheel, until the point moves. This
 >    happens, when point touches the upper window border.
 >
 >    The mark is now moved from the very top of the buffer, to the first
 >    visible line.

I suppose it's due to that change:

2008-04-08  Chong Yidong  <cyd@stupidchicken.com>

	* mwheel.el (mwheel-scroll): Deactivate any temporarily active
	region if point moves.

Could you try to

(1) check your scenario with `transient-mark-mode' disabled, and

(2) check your scenario with Chong's change reverted?

martin