I have a 12K x 6K resolution JPG image. It opens fine. After making an edit, when I try to Save As in Paint.net, the "Save Configuration" dialog appears, with "Preview File Size (computing)" in the right pane. It remains in this state indefinitely (>5 minutes). Clicking OK causes a smaller progress bar dialog to appear: "Save Configuration - Canceling". That dialog also remains indefinitely. There is no Cancel button, and clicking the "X" in the upper right does nothing. Alt-F4 causes it to disappear and be replaced by another dialog "Save Configuration - Finishing". It also remains indefinitely (minutes). Again, there is no Cancel button, and clicking the "X" in the upper right does nothing. Alt-F4 causes it (and the underlying Preview File Size dialog to disappear and be replaced by "Saving - Initializing". Again, no progress after minutes, and no way to dismiss except Alt-F4. This results in an error dialog "There was an error while saving the file".
At this point the normal UI returns and appears to be working.
Is this a known issue?
Running Paint.net 4.09 on Windows 7 / 32 bit.