Make right-click on eraser be secondary (background) color instead of transparent.
Make right-click on eraser be secondary (background) color instead of transparent.

[Fixes bug #678296]

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