Alt+<n> shortcuts doesn't work when terminal (with multiple tabs) restored from saved Xfce session.

Steps to reproduce:
1. run xfce4-terminal
2. Open 2+ tabs
3. make sure tab switching with Alt+<n> shortcuts working
4. save Xfce session
5. re-login/reboot

Expected result:
1. xfce4-terminal should be restored from saved session with multiple tabs.
2. tab switching with Alt+<n> shortcuts should work as usual

Actual result:
1. xfce4-terminal restored from saved session with multiple tabs.
2. Alt+<n> shortcuts does NOT work any more

Workaround:
downgrade to xfce4-terminal-0.8.0 fixes the problem.