Subject: bug#7153: 24.0.50; ediff-clone-buffer-for-region-comparison

From: Stephen Berman <[email-masked]>
Date: Sun, 03 Oct 2010 17:41:45 +0200

1. emacs -Q
2. M-x ediff-regions-linewise, type RET twice to use *scratch* for both
   Ediff buffers (it doesn't matter which buffers are used).
3. Try to select a region with the mouse
=> Emacs beeps and announces the error "mouse-drag-track: The mark is
not set now, so there is no region" 

This happens on any click of the mouse in the buffer.  Nevertheless, it
is possible to select a region by dragging the mouse with mouse-1
pressed.  Subsequently, further mouse clicks do not raise an error any
more.  The bug also happens if I visit a file and call
ediff-regions-linewise on it.

If I comment out the line
    (ediff-activate-mark)
in ediff-clone-buffer-for-region-comparison (in ediff-util.el), then
eval that function, visit a file and call ediff-regions-linewise, then
clicking with mouse-1 does not raise an error.

I observe this bug since r101737, which fixed bug#7044.  That bug
prevented even trying step 3 in the above recipe, so I don't know if the
fix introduced the mouse-drag-track bug or revealed it.

In GNU Emacs 24.0.50.1 (i686-pc-linux-gnu, GTK+ Version 2.18.6)
 of 2010-10-03 on escher
Windowing system distributor `The X.Org Foundation', version 11.0.10605000
configured using `configure  '--without-toolkit-scroll-bars''