* Given an action, find the first 1-key binding (if it exists).
* The LyXKeySym pointer is 0 is no key is found.
* [only used by the Qt/Mac frontend]
* Given an action, find the first 1-key binding (if it exists).
* The LyXKeySym pointer is 0 is no key is found.
* [only used by the Qt/Mac frontend]