Open new tab via GM_openInTab as a child tab of the caller tab (if Tree Style Tab is installed)

I got a feedback about compatibility of my addon "Tree Style Tab" and Scriptish: [Issue #276: GM_openInTab open as child scriptish · piroor/treestyletab](https://github.com/piroor/treestyletab/issues/276).
So, I tried to add a hook for GM_openInTab() to call TST's API before new tabs are actually opened.
However, a simple hack https://github.com/piroor/treestyletab/commit/3b9c542e5a67399830a0597bf10f1e9e1a740ee3 didn't work as I expected.

As stability, I think it is better than such a hack in TST-side that calling TST's API by Scriptish itself.

Or, is there any stable API to add extra hacks for GM_openInTab()?

regards,