martin rudalics <rudalics@gmx.at> writes:

>> 1. C-x C-f <some modified file>
>> 2. M-x vc-ediff
>> 3. Press `n' in the control panel
>> 4. Note that the one of the src buffer - buffer B specifically - becomes
>>    receives focus (or whatever you call it)
>> 5. Pressing another `n' and it modifies the src buffer.
>>
>> I would expect that focus never leave the ediff control panel.
>>
>> Seems like a recent regression to me.
>
> I can't reproduce that here.  But maybe you should try customizing the
> variable `ediff-grab-mouse' to t.

I am debian squeeze running Emacs from trunk (bzr version is visible in
the attached screenshot). Emacs is launched like this:

   ~/src/emacs/trunk/src/emacs  --debug-init -Q

`ediff-grab-mouse' is at it's default value of t.

I am attaching a screenshot of my desktop.  

I don't know whether the diff file has any bearing on the behaviour.
The register.el on display is the one obtained by applying the
bug12389.diff.

This bug is bit of an annoyance.  I am happy you are lookng in to it.