There is an option called "Disable numbered tabswitch" to disable the AltGr+number keybinding. I think that should work for you so you can use Ctrl+AltGr-9. Let me know if that solves your problem.
There is an option called "Disable numbered tabswitch" to disable the AltGr+number keybinding. I think that should work for you so you can use Ctrl+AltGr-9. Let me know if that solves your problem.