Ctrl+Alt+pretty much everything else works. Ctrl+Space works. Alt+Space works. But nothing seems to see Ctrl+Alt+Space.

If I go into System Settings->Keyboard->Shortcuts and try to assign C-A-S to a shortcut, hitting the chord doesn't seem to do anything (that is, the shortcut isn't assigned), but hitting Alt+Space does.

Emacs also doesn't seem to ever receive the key, which is the real problem since Ctrl-Alt-Space is kind of important for certain programming languages. Plan B, in Emacs at least, is the key sequence ESC Ctrl+Space.

I just noticed: Ctrl+Super+Space also doesn't seem to be passed to applications, again, including the keyboard shortcuts app in the System Settings.

1 Answer 1


Unity maps Ctrl+Alt+S to Windows > Toggle Shaded State, whatever that is. If you disable this shortcut, then its passed to whatever application is in that window, including emacs. It is quite confusing though.

  • 1
    Thanks for the suggestion, but Toggle Shaded State is disabled according to my keyboard settings, and it's still not working. Sep 25, 2015 at 14:12

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