Shortcut for "New tab in stack"

[TumbleFur]

I absolutely love the stack-feature, but I think it lacks one critical feature:
A shortcut to open a new tab in the same stack, which is accomplished by clicking on the + sign normally.
Couldn't find this anywhere, so I guess a feature-request is the right way to raise this?

[TumbleFur]

Never mind, i just found out that it depends on how you configure the browser where to open new tabs.
Set it to "next to the current tab" and it'll open a new tab inside the stack.
Default behavior is to open a new tab on the top level.