fn activate_orphan_tabs(tree: &mut Tree<Pane>)Expand description
Draw the docked tree into ui and every popped pane in its own OS window; draw(ui, pane) renders
a pane’s content. A popped window that the user closes is docked back automatically.
Returns (layout changed this frame — caller persists it, a pane was dropped somewhere new).
Repair tab containers whose active no longer names one of their children — which is what leaves a
lone tab drawn as inactive after a rearrange, so it has to be clicked before its pane comes back.