efficient undo/redo in pyqt

[CoolGenie]

Hello,
I'm writing a small component for drawing, in PyQt4. Currently I'm
implementing undo/redo through Qt's framework. I create a list which
contains points, lines, etc. which appear as the user draws on the
screen. On every paint event the list is read, processed and drawn.
This way doing is just adding elements, and undoing is popping them
from the list.
My question: is this an efficient way or could this be done any
better?
The code is here
http://sourceforge.net/svn/?group_id=252201
if anyone is interested.
Best regards,
Przemek