Comment 13 for bug 1958670

While working on bug 1679570 I also figured out and fixed why the "All Files" filter wasn't including files that didn't have extensions - it was using a pattern of "*.*" which of course only includes files with an extension

Another thought I had is that this situation could be improved a bit if Pinta adds an extension to the default filename when saving, e.g. filling it in as "Unsaved image 1.png" (or whatever the last used extension was) rather than just "Unsaved image 1" which immediately puts the user into this scenario