Add support for a Lock screen button - windows-l

When connected to an agent you can ctrl-del-sup with a single click. However when you go to disconnect I find that I often want to leave the machine with the console locked (ctrl-alt-sup>enter or windows+L) and this requires sending another ctrl-alt-sup and clicking on lock from the menu. 

I'd like to suggest that either a button be added to send windows-L or that the close session button be replaced by two buttons. 

- One to just disconnect 

- one to lock the session and disconnect

Or maybe generalize something where you can have a button send a key sequence of your choosing.

Obviously you can't just type windows-l or ctrl-alt-sup> enter as this would lock your local desktop.