wayland: preempt render scheduling in ‘configure’ events

A configure event must be “committed”. In case of resizing, that means
rendering a new frame and committing that surface.

render_resize() will resize the grid and *schedule* a render
refresh. However, if one is already pending, the refresh will take a
very (relatively) long time - until the next frame callback is
received.

This poses a problem when the window is hidden, since in this case,
the frame callback *never* comes. This in turn means we fail to commit
a new surface in response to the ‘configure’ event. And that means the
compositor needs to wait for a transaction timeout before continuing.

The end effect is very slow and jerky window resizing when a hidden
foot window is being resized.

This can happen in tiled compositors, like Sway, where a window can be
tabbed (and thus invisible), but still resized when its container is
resized.

Closes #190

CHANGELOG.md

@@ -21,6 +21,9 @@
 
 ### Fixed
 
+* Resize very slow when window is hidden
+  (https://codeberg.org/dnkl/foot/issues/190).
+
 
 ## 1.5.3