Can't use scroll bar in unity8-deb

[Victor gonzalez]

Story: I can't scroll up or down with the scroll bar in terminal app, however I can do two finger scrolling but is slower when you have a long output on screen. The same terminal app launched in unity7 has a scroll bar that's usable on th right edge.

Environment:
unity8-deb on zesty

Steps:

1. Open terminal in unity8-desktop deb
2. sudo apt update && upgrade
3. Check if you can use the scroll bar to go up

Expected result: scroll bar in right edge to be clickable to scroll up and down
Current result: the scroll bar shows up when doing two finger scrolling but cannot be clicked to scroll up faster