I did a thing and can't undo it

I was editing a .cur and it had many sizes so I extended the .cur viewer to select the size I wanted but now I can't shrink it 'cause the border is out of screen. I tried extending the window sideways but there's a limit, reinstalling, shrinking the "layers" side but those didn't work.
Any ideas how to fix this? Maybe like a soft reset that reset the software to 0?