Control+<Number> as menu shortcuts

[Korodny]

I'd like to customize the menu shortcuts, to make the ones changing styles equal to the ones used in LibreOffice.

LO is using Control+[n] to set header level (0=standard paragraph).

But using number keys as menu shortcuts does not seem to be possible, for some reason? I don't even get a "... is not bound" notification when pressing Control+1 with a default setup, like I get for other unbound keys ("^A is not bound").