bug#61667: 29.0.60; Failure to redisplay

[Po Lu]

Gregory Heytings <gregory@heytings.org> writes:

> How can you draw such a conclusion without knowing what the back
> buffer contains?  The fact that show_back_buffer is called doesn't
> imply that it contains what Dmitry expects to see, namely the contents
> of the xassociations.rb file.

Because, as Dimitry has said:

> And the next one (the last one) happens much later. From further
> testing, it seems to correlate to me typing 'C-x C-c', rather than to
> when the frame finally refreshes after the delay (for example, when I
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> decide to stop waiting and hover with the mouse over the frame, or
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> over the title bar buttons).
> ^^^^^^^^^^^^^^^^^^^^^^^^^^

Hovering over the title bar buttons generates damage on the window and
causes Mutter to ``wake up'', prior to anything further buffer flipping
by Emacs.  Mutter cannot magically pull undisplayed frame contents out
of Emacs.