Currently, the current tab dragging behaviors require too much precision to be even productive with re-arranging tabs. There is a remarked main issue currently in which due to the addition of child tabs in vertical tabs, every single tab has a hover box in which tabs inside of it will become its child tabs when hovered over with a grabbed tab.
The solution should be to move all child tab creations to the left website favicon row, and leave all normal tab behaviors to the right row.
So for example, if a dragged tab was over on the right of the favicon row, then instead the tab will be a parent tab. If it was on the left however, it would be a child tab.
Exceptions to this rule may apply for tabs which are nested child tabs of another child tab.