Fix crash in early window raise in gtk3.

anntzer · anntzer · commit 1335c6ce2959 · 2021-03-10T12:23:40.000+01:00
Repro:

    import matplotlib as mpl
    import matplotlib.pyplot as plt
    mpl.use('GTK3Agg')
    plt.figure().canvas.mpl_connect('resize_event', lambda e: plt.pause(1))
    plt.show()
diff --git a/lib/matplotlib/backends/backend_gtk3.py b/lib/matplotlib/backends/backend_gtk3.py
@@ -392,7 +392,14 @@ def show(self):
         self.window.show()
         self.canvas.draw()
         if mpl.rcParams['figure.raise_window']:
-            self.window.present()
+            if self.window.get_window():
+                self.window.present()
+            else:
+                # If this is called by a callback early during init,
+                # self.window (a GtkWindow) may not have an associated
+                # low-level GdkWindow (self.window.get_window()) yet, and
+                # present() would crash.
+                _api.warn_external("Cannot raise window yet to be setup")
 
     def full_screen_toggle(self):
         self._full_screen_flag = not self._full_screen_flag
