Parameters
hMenu
Handle to the menu that contains the menu item.
uItem
Identifier or position of the menu item to change. The meaning of this parameter depends on the value of fByPosition.
fByPosition
Value specifying the meaning of uItem. If this parameter is FALSE, uItem is a menu item identifier. Otherwise, it is a menu item position.
lpmii
Pointer to a MENUITEMINFO structure that contains information about the menu item and specifies which menu item attributes to change.
可能是hMenu 就包含了你所设置的菜单的句柄,包含了子菜单!!