It should be, if it isn’t then it must’ve been added after 4.7 was branched, so will be in 4.8 instead.
Your second video looks like your cursor position is in screen-space, rather than in the space of the widget you’re transforming against. You might want to take a look at FGeometry::AbsoluteToLocal to see if that can help you here (you’ll actually need to get the widget geometry somehow to perform an accurate transformation).