Return Code	Significance
0	all OK
1	old menu-listener function was overwritten
-1	No menu Id passed

With the help of the menu-listener callback function you can react on changes to the local data structure. The menu-listener function is automatically invoked by all functions that change menus, such as dal_men_wri_row.

The menu-listener function must correspond to the specification void fnc(idm, typ, fnc_nam, par). The parameters are:

• DtvLong idm: Menu Id
• DTV_LAY_LNR_TYP typ: Enumeration type, for menus DTV_LAY_MEN
• char *fnc_nam: Name of the menu-changing calling function
• DtvLong par: Row of the calling function or 0

If the same listener function is used for all objects (menus, button areas, masks), the enumeration type DTV_LAY_LNR_TYP can be used to determine from which object the listener function was called.