It sure looks broken. When I open in Composer instead of Simple, it'll work completely different for input. CTRL-z doesn't work in either of them. I'll try your suggestion and report.
Ludo
> In File the last entry is Quit. Apart from the 3 Open(s) I mentioned,
> there's new file, new tab, save ,save as, print preview, print part.
> No more.
This installation would seem to be broken. Can you hide ~/.denemo and
try again. I think an old version may be breaking things.
cd
mv ~/.denemo ~/.denemoHIDDEN
and re-run denemo.
You will have to re-set ctrl-k unfortunately.