For example, it would be very handy to call xfce4-session-logout by one hotkey (set up in the xfwm4 settings) and then immediately select the desired action by another hotkey, not touching mouse or any arrow keys on the keyboard.
You can add custom keyboard shortcuts or Alt+F4 on the desktop to open the logout dialog. The dialog itself has support for Alt+key mnemonics.
Created attachment 4281 screenshot of the logout dialog I'm sorry, but how can I use the Alt-key mnemonics? As you can see, there are no hotkey hints, even if I press Alt.
Well that was added in 4.8, but it is possible you translation is missing them.
Thanks for your help! I'll try to write a patch for the translation (I'm using Xfce 4.8 from Debian Wheezy).