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WM_COMMAND Notification
The WM_COMMAND message is sent when the user selects a command item from a menu, when a control sends a notification message to its parent window, or when an accelerator keystroke is translated.
Syntax
WM_COMMAND
WPARAM wParam
LPARAM lParam;
Return Value
Remarks
Use of the wParam and lParam parameters are summarized here.
Message Source wParam (high word) wParam (low word) lParam
Menu 0 Menu identifier (IDM_*) 0
Accelerator 1 Accelerator identifier (IDM_*) 0
Control Control-defined notification code Control identifier Handle to the control window
Menus
If an application enables a menu separator, the system sends a WM_COMMAND message with the low-word of the wParam parameter set to zero when the user selects the separator.
Windows 98/Me, Windows 2000/XP: If a menu is defined with a MENUINFO.dwStyle value of MNS_NOTIFYBYPOS, WM_MENUCOMMAND is sent instead of WM_COMMAND.
Accelerators
Accelerator keystrokes that select items from the window menu are translated into WM_SYSCOMMAND messages.
If an accelerator keystroke occurs that corresponds to a menu item when the window that owns the menu is minimized, no WM_COMMAND message is sent. However, if an accelerator keystroke occurs that does not match any of the items in the window's menu or in the window menu, a WM_COMMAND message is sent, even if the window is minimized.
Notification Requirements
Minimum DLL Version None
Header Declared in Winuser.h, include Windows.h
Minimum operating systems Windows 95, Windows NT 3.1