WM_CONTEXTMENU message

Notifies a window that the user desires a context menu to appear. The user may have clicked the right mouse button (right-clicked) in the window, pressed Shift+F10 or pressed the applications key (context menu key) available on some keyboards.

#define WM_CONTEXTMENU                  0x007B

wParam

A handle to the window in which the user right-clicked the mouse. This can be a child window of the window receiving the message. For more information about processing this message, see the Remarks section.

lParam

The low-order word specifies the horizontal position of the cursor, in screen coordinates, at the time of the mouse click.

The high-order word specifies the vertical position of the cursor, in screen coordinates, at the time of the mouse click.

No return value.

A window can process this message by displaying a shortcut menu using the TrackPopupMenu or TrackPopupMenuEx functions. To obtain the horizontal and vertical positions, use the following code.

xPos = GET_X_LPARAM(lParam); 
yPos = GET_Y_LPARAM(lParam); 

If a window does not display a shortcut menu it should pass this message to the DefWindowProc function. If a window is a child window, DefWindowProc sends the message to the parent. Otherwise, DefWindowProc displays a default shortcut menu if the specified position is in the window's caption.

DefWindowProc generates the WM_CONTEXTMENU message when it processes the WM_RBUTTONUP or WM_NCRBUTTONUP message or when the user types SHIFT+F10. The WM_CONTEXTMENU message is also generated when the user presses and releases the VK_APPS key.

If the context menu is generated from the keyboard for example, if the user types SHIFT+F10 then the x- and y-coordinates are -1 and the application should display the context menu at the location of the current selection rather than at (xPos, yPos).

Reference

DefWindowProc

GET_X_LPARAM

GET_Y_LPARAM

TrackPopupMenu

TrackPopupMenuEx

WM_NCRBUTTONUP

WM_RBUTTONUP

Conceptual

Menus