Display issues when zoomed in (I highlighted with red circles, those lines should be straight (it's a screenshot from desktop)). It mostly happens at 300% or 400% zoom and if pant.net window is maximised. Disabling hardware acceleration fixes the problem. Something similar happens while you do a selection with (in this case) 400% zoom. Note the inside of the selection, certain pixels moving their position. These two are regressions from 4.0.9. Also, on a non related note, would be nice if paint.net would offer the possibility to compress JPEGs even less than what it currently does at 100% quality.