Hi there, long time user of paint.net here.
The one feature that's always been missing for me is individual color channel editing (a standard feature in bigger packages like gimp and photoshop). There are some plugins I use to remedy this missing feature but none are quite elegant enough. Paste alpha comes to mind. It allows me to edit the alpha channel as greyscale.
Now I understand paint.net being a simpler tool, adding a new "channels" window is probably out of the question, so it needs to be implemented cleverly.
Perhaps something like this:
Perhaps ctrl+clicking a channel checkbox would show it exclusively and in greyscale.
This was the first implementation that came to mind, there might be more elegant solutions.
