Explicitly set window size after fullscreen(): some WMs do not like fullscreen()...

diff --git a/qwerty.py b/qwerty.py
index d811296..38ddbc5 100755
--- a/qwerty.py
+++ b/qwerty.py
@@ -613,6 +613,8 @@ class GUI(object):
         self.fullscreen = fullscreen
         if self.fullscreen:
             self.window.fullscreen()
+            w,h = self.window.get_screen().get_width(), self.window.get_screen().get_height()
+            self.window.resize(w,h)
             self.width, self.height = self.window.get_screen().get_width(), self.window.get_screen().get_height()
         else:
             self.window.parse_geometry(geometry)