Hi there, I just made this account to notify you guys of this, I solved it by unchecking the box for the Hardware Accelerated Rendering (GPU) in the options menu, and it solved all problems. I did check through the forum (although only the newest threads) as I updated to paint.net 4.0 as the notification told me about it, and so far I have to say that I love every single change that you've made so far. Anyways, the problem I had was that whenever I used ctrl + tab and ctrl + shift + tab to switch between images, any tools as well as zooming or scrolling suddenly stopped working in the main field. I could continue draw and do stuff, but I didn't see any changes other than in the history window, which made it really hard to know whether I drew right. I solved it by selecting all, copying, making a new image (with the same size), pasting, and then the changes I did to the last image was there, and I could go back to it and continue editing. But this happened so often, and I couldn't see why. I was focused on the main drawing field, and I could scroll and zoom, but it didn't show any changes other than on the surrounding UI. I have a (3-year-old) laptop with an i5-2410M CPU with 4 cores, rest of the specs here:
