In case anyone might wonder what OS version of Windows 10 I'm using, I'll tell you now; it's Build 10122. I know (I'm actually not sure, but I do recall him talking about using it) that Marc is using Windows 10, so he might experience this problem too, but I could of course be wrong. But right now, I find Craftland unplayable with this problem. If anyone else is using Windows 10, don't update it, if you don't want this ridiculous problematic border.
The problem may not seem very severe, but it definitely is a huge problem.

P.S. I don't think Nidefawl or anyone else can fix this problem, and I would have to wait for a new update to Windows 10. Help me Microsoft and developers of Craftland, you're my only hope.