[Fixes bug #1075799] Fix undo for the Finish Pixels action.
[Fixes bug #1075799] Fix undo for the Finish Pixels action.

jakeclawson/Pinta,Fenex/Pinta,PintaProject/Pinta,Mailaender/Pinta,PintaProject/Pinta,PintaProject/Pinta,Mailaender/Pinta,Fenex/Pinta,jakeclawson/Pinta