My patch for Krita is done. It was less than a week to do, so the review and commit process was quite fast (perhaps because the simplicity of the function). So a big thanks for Sven, for the reviews and tips, and Boudewijn, for the commit.
In the wishlist, the problem was specified as simply associate the Delete shortcut to the Clear action in the Edit menu. In a first glance, I saw that the key was bound to another operation. Asking on #krita IRC channel, Sven said that the task was a little more than simply adding a shortcut. You see, to work with shapes (squares, circles, stars, etc) Krita uses the Flake library, thus the application have two different actions, one to deal with pixels and other to deal with shapes. The job was to merge the two actions in one (in this case, the Clear action). I made a little video to show the results:
So, the thing works !:D
See ya later!