bk138/gromit-mpx — pull request #8 by nwhitehead (2013-10-16 07:27:41+00:00)
Title: Add simple undo functionality.

An extra backing surface is used to record the screen state between
strokes. Adds "gromit-mpx --undo" and "gromit-mpx --redo" commands.
Both have the same effect, swap undo backing surface and current
backing surface. Prepares for future multiple levels of undo and redo.