How to open new non-empty tab as first child

[Kuba314]

Hi!

After middle-clicking a link or right-clicking and selecting "Open Link in New Tab", I'd like the new tab to be opened as a first child tab.

Opening a new empty tab (ctrl+T) already does this for me. I'd like non-empty tabs to behave the same way. Sadly, I can't seem to find the right checkbox for this.

Current beaviour:

Parent:
  \- old child
  \- new child

What I'd like to see:

Parent:
  \- new child
  \- old child

[irvinm]

Under "Tree Behavior":

Other:

I already have this behavior by setting the default position "next to the current tab" by setting the Firefox about:config parm:

[Kuba314]

Thank you so much! It was the first option you mentioned. I couldn't find it before. It works now!