User Menu Item Label
User Function which is invoked each time a User Menu Item is about to displayed and will return, if required, a different Label for that menu item.
important
This is used for both Column Menus and Context Menus.
The handler
recieves a Menu Info object which provides full information of the column / cell where the menu is being displayed and returns a label value.
handler: (menuInfo: MenuInfo) => string;
tip
Return an empty string to use the default Label value for the User Menu Item