I'm a Joe newbie, and didn't find how to Undo a command (while logged on remotely through Putty.)
On my French keyboard, I can't use Undo/Redo with CTRL_ and CTRL^, respectively. Maybe this combination is hard-coded for the US keyboard layout.
For Undo, I tried CTRL9 followed by AltGr9, to no avail.
Does someone know if the commands are US-specific, and if yes, how to get those to work on other keyboards?