KEY
Associates a key to a menu or submenu item. Such key works as a shortcut when the menu is open.
Value
String containing a key description. Please refer to the Keyboard Codes table for a list of the possible values.
Default: NULL
Notes
IUP automatically underlines the first appearance of the chosen menu letter. For such, the chosen letter must necessarily be a part of the menu text.
In the menu bar, some systems automatically associate the ALT+<letter> combination for the chosen letter. This is valid for the Windows driver, but not for the Motif driver.
Be careful not to misuse this attribute in relation to K_ANY callback.