[OS X Emacs] trouble with ediff? or standard behavior? (was: trouble with ediff after updating Aquamacs)

[David Reitter]

On Oct 6, 2016, at 10:22 AM, Thomas Käufl <kaeufl at online.de> wrote:

> The Gnu Emacs (24.5) does not show this behaviour.
> 
> As the control panel is necessary to visit the differences
> of two buffers, it seems to me, that there is an error
> in the new version of Aquamacs.

I’m not trying to sound overly defensive, but keep in mind that Aquamacs comes with different configuration for frame and windowing behavior.  These configurations often achieve the right results overall, but they also bring out weaknesses in Emacs modules, such as  ediff in this case.  The same goes for individual configurations that you might have.

The first step to isolate problems is to run Aquamacs without customizations via the Help -> Diagnose menu.

If the problem persists, you would need to look at the ediff code.  C-h f ediff RET should give you help, and clicking on the source file at the top will take you to the lisp code that makes ediff work.  Look for how these buffers are displayed (`pop-to-buffer’, `switch-to-buffer’), if new frames are made and how.  It is likely that the ediff designers made assumptions about where frames appear, and which buffers appear in separate frames, and that these assumptions aren’t warranted given that Emacs can be configured.  

Of course it is entirely possible that we somehow destroy documented behaviors in Aquamacs, or in Emacs 25.1.  Finding out what’s happening is the key to making Emacs / Aquamacs better.   You do have to dive into the code to get there!


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