LMB on desktop without any children causes crash

What steps will reproduce the problem?
1.   desktop = gui.Desktop()
2.   while not selection:
3.     desktop.update()
4. click LMB

What is the expected output? What do you see instead?
Traceback (most recent call last):
  File "C:\rgn_game.py", line 71, in <module>
    rgn_file = select_dialog(files)
  File "C:\rgn_game.py", line 57, in select_dialog
    desktop.update()
  File "C:\simple_pygame_gui\gui.py", line 590, in update
    if self.focused and self.focused != self:
AttributeError: Desktop instance has no attribute 'focused'

What version of the product are you using? On what operating system?
SPG SVN r31

Please provide any additional information below.

Index: gui.py
===================================================================
--- gui.py  (revision 31)
+++ gui.py  (working copy)
@@ -543,6 +543,8 @@
         self.onClick = None
         self.onMouseDown = None
         self.onMouseMove = None
+
+        self.focused = None

         self.size = pygame.display.get_surface().get_size()

Original issue reported on code.google.com by techtonik@gmail.com on 16 Jun 2008 at 1:18

google-code-export / simple-pygame-gui

LMB on desktop without any children causes crash #4