send_about_to_show

Description:

public void send_about_to_show (void* cb, void* cb_data)

This function is used to send the even that the submenu of this item is about to be shown.

Callers to this event should delay showing the menu until their callback is called if possible.

this	The Menuitem to send the signal on.
cb	Callback to call when the call has returned.
cb_data	Data to pass to the callback.