Fixed an issue where scrollbar parts move to negative y coordinate

[RESTRICTED ACCOUNT]

The vertical parts of the scrollbar can be moved to negative coordinates, creating a strange look and at the same time losing functionality.
I don't know if this happens in standard, but it's an issue that happens in extended.

Buttons that trespass into negative coordinates cannot be pressed. Therefore, there is no reason to allow the trespass.



The patch will fix it as follows



I haven't checked if the same problem occurs in the horizontal direction. (´・ω・｀)

[prissi]

Thanks, incorporated in r9973