[Feature Request] Parent/Sub Tabs

[seniorm0ment]

Similar to TreeStyleTabs, it would be amazing to be able to have the option of tabs open within one another (So you have a parent tab, then subtabs inside there that can collapse and expand) to clean things up.

And have this auto populate so that it can auto do this if it's the same domain.
Example: Open Reddit, then click a link inside of reddit, it keeps Reddit open and sets that as parent tab, then automatically opens the link as a subtab.