It is currently not possible to extend this screen vertically for some reason while horizontally does work (Mendix 7.15.1)
It's getting kind of annoying when you're going through visibility settings with a multitude of module roles and have to scroll up and down when checking. It would be highly appreciated if this could change!
EDIT: Same for the edit attribute screen. it's less important in my eyes, but it's peculiar that screens can be extended indefinitely horizontally, but are limited to a certain size vertically
EDIT: The security page (in project security) also can not be vertically extended