Smudge Tool with Sample Merged Option
Description of the feature
An interesting feature to introduce is the Sample merged (as is possible see on Clone Tool). This renders possible to smudge paint on an empty transparent layer, pulling the colors from the underlying visible layers. This would make it very easy to go back and correct or repaint according to changing artist goals.
As comment 6 in the original Bugzilla report says the developer (Shark0r), of the new features, about jose americo gobbo's suggestion:
Sample merged option (as we have in the Clone tool). Haven't thought about this yet. Maybe easier to implement...