Consider adding an active tab line to the terminal tabs list

[Tyriar]

One annoyance I've had with tabs is that it's sometimes difficult to tell what the active item is because we rely so much on the selection which can change (plus bugs can slip in like #127357).

How about using the editor's selected tab border color and overriding with a terminal-specific one if present?

@misolori what do you think? Note that I have it overlapping the sash right now which should be fine as long as it ignored pointer events.

[miguelsolorio]

yea this looks great. Also similar in notebooks, we also show a slightly thicker and offset indicator:

but i think what you show better mirrors the active panel/editor border

[Tyriar]

Unfortunately it wasn't really doable without a bunch of hacks to replace the existing sash line: