This system-provided window procedure processes the actions on a menu control (WC_MENU).

Purpose

A menu control is a child or pull-down window that contains a list of selection items. These items can be represented by text strings, separators, bit maps or menu buttons. Menu templates can be loaded as resources and the menu can be created automatically when the parent window is created. The application can build the menu dynamically by sending MM_INSERTITEM messages. An application can change a menu by sending messages to it.

Menus enable the operator to select one of the items in the list, using the pointing device or the keyboard. When a selection is made, the menu parent is notified by posting a WM_COMMAND, WM_SYSCOMMAND, or WM_HELP message and a unique identifier representing the operator's selection.

Menus automatically resize themselves when items are added and removed. Menus are automatically destroyed when their owner is destroyed.

Typically, an application has an action bar menu and several submenus. The action bar is normally visible, and is a child window in the parent window frame. The submenus are normally hidden and become visible when selections are made on the action bar.