Indent child tabs to indicate parentage

[desrod]

Feature request, not so much a bug: Like Tree Style Tab and Tab Groups, can we get a way to indent child tabs under their parent tab, so it's visually apparent which tab was launched from which parent tab?

Eg: If I'm on a site and cmd+shift+click a link, it opens below the tab I'm on, but it would be nice if it was indented to show that position, vs. lining up directly to the left, appearing as a 'top-level' tab.