[mutter] wayland/xdg-shell: Do not maximize if not possible

[Jonas Ådahl <jadahl src gnome org>]

commit 6fe46cac60c95e17dd5cd8c7b11aecfe1da5a18c
Author: Olivier Fourdan <ofourdan redhat com>
Date:   Fri Feb 15 09:31:04 2019 +0100

    wayland/xdg-shell: Do not maximize if not possible
    
    On X11, if a window cannot be maximized because its minimum size is
    already larger than the output size, a request to maximize will be
    ignored.
    
    On Wayland, however, we would still honor the maximize request and
    switch the window state to maximized, without actually moving the window
    which leads to weird visual effects, as the window end up being
    maximized in-place.
    
    To avoid this, make sure the window has the maximize functionality
    available prior to change its state in xdg-shell `set_maximized`
    request.
    
    Closes: https://gitlab.gnome.org/GNOME/mutter/issues/463

 src/wayland/meta-wayland-legacy-xdg-shell.c | 3 +++
 src/wayland/meta-wayland-xdg-shell.c        | 3 +++
 2 files changed, 6 insertions(+)
---
diff --git a/src/wayland/meta-wayland-legacy-xdg-shell.c b/src/wayland/meta-wayland-legacy-xdg-shell.c
index 504b34ffd..1523481d4 100644
--- a/src/wayland/meta-wayland-legacy-xdg-shell.c
+++ b/src/wayland/meta-wayland-legacy-xdg-shell.c
@@ -397,6 +397,9 @@ zxdg_toplevel_v6_set_maximized (struct wl_client   *client,
   if (!window)
     return;
 
+  if (!window->has_maximize_func)
+    return;
+
   meta_window_force_placement (window, TRUE);
   meta_window_maximize (window, META_MAXIMIZE_BOTH);
 }
diff --git a/src/wayland/meta-wayland-xdg-shell.c b/src/wayland/meta-wayland-xdg-shell.c
index c7e738357..afd4bb94b 100644
--- a/src/wayland/meta-wayland-xdg-shell.c
+++ b/src/wayland/meta-wayland-xdg-shell.c
@@ -393,6 +393,9 @@ xdg_toplevel_set_maximized (struct wl_client   *client,
   if (!window)
     return;
 
+  if (!window->has_maximize_func)
+    return;
+
   meta_window_force_placement (window, TRUE);
   meta_window_maximize (window, META_MAXIMIZE_BOTH);
 }