Is it possible to change the behavior of middle clicking a link as a sibling tab instead creating a child of current tab?

[sibuting921]

I often use tab group to organize my tabs on chrome.
have tried 'simple tab group's add-on on firefox, but the groups are under a add-on icon instead.
I realize 'tree style tab' is most likely to reach same function as to use parent tab as a group.
How can I change the behavior of middle clicking a link as a sibling tab instead creating a child of current tab?
Maybe it can be a new project for tab grouping add-on.

as:

wish:

chrome tab group

'Simple Tab Groups' are all under a add-on button , it should be named as 'Simple Workspaces'

[sibuting921]

It can work after the indent level changed from -1 to 1.

This comment answer my question in different way.
Can I make TST create only two levels of tree? #3396