[mutter] window: Store unconstrained_rect everytime a size is requested

[Marge Bot <marge-bot src gnome org>]

commit 6902a724ce0f89ef448ae46adeab055630c30bec
Author: Sebastian Keller <skeller gnome org>
Date:   Wed Oct 27 23:44:47 2021 +0200

    window: Store unconstrained_rect everytime a size is requested
    
    Currently the stored unconstrained_rect is only ever updated if there
    was a move, resize or state change according to the move_resize_internal
    implementation.  For Wayland windows however resizes or state changes
    are done in two steps, first the new configuration is sent to the client
    and then once client acknowledges it, it is set on the mutter side in
    another move_resize_internal call. Only the second call would result in
    the unconstrained_rect being updated.
    
    This started causing problems when unfullscreening windows was
    immediately followed by a strut change. These strut changes started
    happening in gnome-shell due to the visibility of the panel now being
    considered for the struts and the presence of a fullscreen causing it to
    be hidden until unfullscreen. In this situation first the unfullscreen
    would resize the window to its pre-fullscreen size as expected, but then
    the strut change triggers another window resize. This window resize is
    based on the stored unconstrained_rect, which is still at the fullscreen
    size because the unfullscreen resize only has sent its configuration,
    but it has not been acknowledged yet. As a result the strut change
    causes a resize to the fullscreen size which due to the constraints now
    looks like a maximized window.
    
    To fix this always update the unconstrained_rect when the requested size
    has changed, but not when a previous request has been acknowledged
    unless it is originating from the client itself.
    
    If this included the move_resize_internal call from acknowledging the
    size as well, it would be possible for this to be delayed long enough on
    the client side to overwrite an intermediate resize originating from
    mutter. And if this did not include resizes originating from the client,
    clients would not be able to set an initial window size.
    
    Fixes https://gitlab.gnome.org/GNOME/mutter/-/issues/1973
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2066>

 src/core/window.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
---
diff --git a/src/core/window.c b/src/core/window.c
index 0f0c644d6d..ff4816eea8 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -4162,8 +4162,13 @@ meta_window_move_resize_internal (MetaWindow          *window,
       g_signal_emit (window, window_signals[SIZE_CHANGED], 0);
     }
 
-  if (moved_or_resized || did_placement)
-    window->unconstrained_rect = unconstrained_rect;
+  /* Only update the stored size when requested but not when a
+   * (potentially outdated) request completes */
+  if (!(flags & META_MOVE_RESIZE_WAYLAND_FINISH_MOVE_RESIZE) || 
+      flags & META_MOVE_RESIZE_WAYLAND_CLIENT_RESIZE)
+    {
+      window->unconstrained_rect = unconstrained_rect;
+    }
 
   if ((moved_or_resized ||
        did_placement ||