bug#36680: 27.0.50; undo-tree visualizer flickering with display-buffer-reuse-frames -> t

[martin rudalics]

> (setq display-buffer-reuse-frames t)
> (require 'undo-tree)
> (undo-tree-mode)
>
> Make some further edits to scratch for testing.  Then
>
> C-x 5 2
> C-x u
> [up]...
>
> Any time you switch the current node in the visualizer, the first frame
> is raised for a very short time, then lowered again.  This is quite
> annoying, it makes C-x u quite useless when you have a window in another
> frame displaying the current buffer because it distracts me from seeing
> what changes in the buffer, I'm unable to see it.  Setting
> display-buffer-reuse-frames -> nil fixes this.
>
> The visualizer calls
>
>    (switch-to-buffer-other-window undo-tree-visualizer-buffer-name)
>
> which doesn't seem to behave well in this situation.

I don't know why 'undo-tree' apparently insists on switching to its
buffer here but if you put it on another frame you have to live with
the fact that that frame will be raised.  I think you should make a
special rule for 'display-buffer' to not display the undo tree on a
separate frame.  Note also that 'display-buffer-reuse-frames' is an
obsolete variable.

martin