More work on cthulhu recognizing focused items that should be read.

tests/gtk_window_switcher.py

@@ -24,6 +24,9 @@ if providerName == "marco":
         raise RuntimeError("cannot set fixture process name")
 
 window = Gtk.Window(title="Switcher fixture " + providerName)
+# Label updates must not resize the foreground window while the test compares
+# its full X11 snapshot to check that the switcher has not taken ownership.
+window.set_default_size(400, 100)
 if providerName == "marco":
     window.set_accept_focus(False)
     window.set_focus_on_map(False)