I just mean the rectangle select tool -- but that's not the issue. The issue is simply that when I use paint bucket once, and then "finish" using it, the paint bucket no longer works subsequently. I have to close and restart the program to get it to work again. The same thing happens after inserting text: when trying to add text again later, no text appears (although the cursor moves on, as if the text is being inserted somewhere.) And I do make sure i've got the right layer selected, etc.
I never had this problem before the newest update.
Edit: I think I've figured it out. I just noticed that I had an "unfinished" selection in another open paint.net file. I "finished" that selection, then went back to the file I was working on. Then things worked properly, so far as I've tested.
Thanks for listening!