The behavior you describe that you want is actually the default. It is controlled by the Display Automatically setting in Tools->Tool Properties, under General/SQL Commander/Auto Completion.
Ctrl-Space triggers Auto Completion manually by default, but you can bind it to another key combination in Tools->Tool Properties, in the General/Key Bindings category. In the Action tree, it is found under Main Menu/Edit as Show Auto Completion.
Oh Wow, I had no idea that shortcut existed. Thanks for letting me know. Maybe a note can be added to the auto-complete tool options tab to indicate that the shortcut exists so others like me don't have to wonder?
You're right. There will be a reference to the shortcut in the next maintenance release.
In SQL Commander, I have had to disable the autocompletion feature because it constantly pops up when I don't want it - but it would be handy to have it for when I do want it.
Having a configurable keyboard shortcut for this functionality, thus making it "non-auto" would be wonderful. Then I could hit some key combination (ctrl+somekeyhere) and it would give me that popup, but I can conveniently code away without annoying popups when I am working on schema's I already have memorized.