[BUG] Scrollbar only has 2 pixels of width to grab

[BrodieRobertson]

It appears that this issue had been resolved in the past, so I think this may be a regression https://github.com/pop-os/cosmic-term/issues/381

That issue seemed to indicate that when you get close to the scrollbar, the grab area should increase in size, however that doesn't seem to occur.

[WatchMkr]

The scroll bar should become wider when the cursor is over it. There's room for improvement nonetheless.

(before hovering over the scroll bar)

(hovering over the scroll bar)