I'm a new user, and not a graphic designer or power user, and trying out the software for the first time everything seemed fantastic, until I suddenly found that "Erase Selection" would not work, no matter what I tried, with just the one layer shown (so I was definitely editing that layer!)
I was about to give up on the software, when I worked it out: in the Layer Selector, only one layer was ticked for displaying, yes, but the pale highlight was on a different layer. Turns out, I was genuinely making all those attempted edits/deletions to a different, invisible layer...
I'm sure you all know this and, sure, once you learn this is possible, and learn to be a bit more careful, it's not a problem – but it is perhaps a problem for losing potential new users like me, before they become "users"(!) - to me, testing out the software, this just seemed like some *enormous* bug, or hideous UI: I could not make "Erase Selection" work.
Maybe all pro graphic design tools do this, I wouldn't know. But I guess actually it *is* a very strange thing for any software to be doing, to be making changes to an invisible layer, invisibly? When I can't possibly be making any "edits" accurately/intentionally? So I wonder: if the software finds itself doing that, could it maybe display some small warning, along the lines of "the layer you're editing is not currently shown"? (I'm assuming there is some reason why the situation is allowed in the first place?!)
PS As I know so little about graphic design or paint.net, this post (my first) could easily be idiotic or inappropriate – apologies in advance, if so.
PPS Thanks, it does seem pretty amazing software.