Make gtk3 full_screen_toggle more robust against external changes.

anntzer · anntzer · commit 40d76b68487c · 2021-11-10T23:09:48.000+01:00
The fullscreen state can also change via the window manager, so read the
state instead of trying to keep an internal flag.  All other backends
already use a similar strategy.

(`self.window` is a GtkWindow, whereas `self.window.get_window()` is a
GdkWindow...)
diff --git a/lib/matplotlib/backends/backend_gtk3.py b/lib/matplotlib/backends/backend_gtk3.py
@@ -395,12 +395,10 @@ def show(self):
                 _api.warn_external("Cannot raise window yet to be setup")
 
     def full_screen_toggle(self):
-        self._full_screen_flag = not self._full_screen_flag
-        if self._full_screen_flag:
-            self.window.fullscreen()
-        else:
+        if self.window.get_window().get_state() & Gdk.WindowState.FULLSCREEN:
             self.window.unfullscreen()
-    _full_screen_flag = False
+        else:
+            self.window.fullscreen()
 
     def _get_toolbar(self):
         # must be inited after the window, drawingArea and figure
