Error on 'Close' press

[nathanin]

Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1540, in __call__
    return self.func(*args)
  File "./ImageLoadGUI.py", line 47, in <lambda>
    self.buttonClose(arg1))
  File "./ImageLoadGUI.py", line 330, in buttonClose
    self.image.canvas.delete(self.image.activebox)
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 2343, in delete
    self.tk.call((self._w, 'delete') + args)
TclError: invalid command name ".140679427181600.140679427182464"

I think it's because I opened, and closed, a couple images with the OS window 'x' button. Add a signal to close windows doing this workflow.