ctrl-space doesn't work

[Glenn Holmer]

Trusty daily with all updates.

I'm finding that ctrl-space shortcuts don't work, for example in 
NetBeans for code completion, or in emacs to set the mark. If I drop 
down to a console (ctrl-alt-F1) and run emacs there, the key combination 
works.

I've looked through the keyboard shortcuts in the settings dialog under 
"Shortcuts and Gestures", but don't see anything bound to ctrl-space.

Is anybody else seeing this? Where else can I look to see if something 
is binding that combination?

-- 
Glenn Holmer (Linux registered user #16682)
"After the vintage season came the aftermath -- and Cenbe."