diff --git a/gui/toplevel.py b/gui/toplevel.py
index 5881009..7e0333e 100644
--- a/gui/toplevel.py
+++ b/gui/toplevel.py
@@ -70,6 +70,10 @@ class _ToplevelState(object):
     def set_font(self, font_name):
         gui.startup.send_to_gtk(lambda: self._do_set_font(font_name))
 
+    @in_gtk_thread
+    def windows(self):
+        return self.toplevels.values()
+
 state = _ToplevelState()
 
 class Toplevel(object):