Returns the position of the underlined character in the menu item title used as a mnemonic.
- macOS 10.0–10.6Deprecated
The position is the zero-based index of that character in the title string. If the receiver has no mnemonic character, returns
Sets the character of the menu item title at location that is to be underlined.
Returns the character in the menu item title that appears underlined for use as a mnemonic.