Selected tab underline thickness is hard to see

[wavebeem]

I would like there to be a way to customize the active tab underline thickness. The current 1px thickness is difficult to notice. I think 4px makes sense.

Existing tab UI

It's hard to tell which tab is selected, especially in light themes where a thin dark line isn't generally noticeable.

Tab UI suggestion

There's plenty of room to add a 4px line, which fits with the WCAG focus suggestion of using color the size of twice the perimeter of the shape being outlined. This is both easy to see and aesthetically pleasing, in my opinion. This isn't the same thing as component focus, but if it's good enough for focus, I think it should be good enough for active state.

Other small underlines

The top/bottom docked activity bar has the same issue

As do the tabs in the panel and in the terminal

Other programs

WebStorm uses a 4px border which is easy to see.

Other GitHub issues

A similar previous request was locked (due to inactivity?) #130394