[Terminal] Scrollback buffer becomes invisible

[diver]

This is hrev47371.

Scrolling back with mouse makes some lines disappear. They becomes visible again after selecting them or resizing a window. To reproduce:

while true ; do echo Haiku ; done

and scroll up.

[bonefish]

I'm pretty certain I haven't seen such an issue in the time after I reworked the terminal buffer handling and drawing code in 2010. I think I first noticed drawing issues some time after Adrien worked on the color support, though I didn't experiment to find a simple reproducible test case.

[waddlesplash]

Still here in hrev52781.