Here's my solution from a previous question:
You can use
tab_selected(int tab) signal from each tab and trigger a one shot timer whenever a click event is received. If a click occurred while the timer is active (double click), popup a dialog that contains a LineEdit, confirmation button and a cancel button. when the user confirms, use
set_tab_title() to edit the title.
Make sure you pass up the tab number from
tab_selected(int tab) so that you know which tab to change its title.