The custom resolution input fields are broken.
If you enter a custom number or hit backspace, the text field does not properly update. Instead, the new characters just smear over the text field, quickly resulting in unreadable text.

Also, you can enter letters.

Finally, I never seem to get the custom resolution to work in the first place in window or fullscreen mode. It seems my input is just ignored The resulution/window size changes, but rarely to the size I have entered. (What I do: 1. Click “Custom” 2. Enter numbers 3. Click OK).

Version: 6a81340
Tested on GNU/Linux, Phython 3.8.1