WM_PARENTNOTIFY
fwEvent = wParam; /* event flags */
wValue1 = LOWORD(lParam); /* child handle/cursor x-coordinate */
wValue2 = HIWORD(lParam); /* child ID/cursor y-coordinate */The WM_PARENTNOTIFY message is sent to the parent of a child window when the child window is created or destroyed or when the user clicks a mouse button while the cursor is over the child window. When the child window is being created, the system sends WM_PARENTNOTIFY just before the CreateWindow or CreateWindowEx function that creates the window returns. When the child window is being destroyed, the system sends the message before any processing to destroy the window takes place.
fwEvent
Value of wParam. Specifies the event for which the parent is being notified. It can be any of the following values:
| Value | Description |
| WM_CREATE | The child window is being created. |
| WM_DESTROY | The child window is being destroyed. |
| WM_LBUTTONDOWN | The user has placed the mouse cursor over the child window and clicked the left mouse button. |
| WM_MBUTTONDOWN | The user has placed the mouse cursor over the child window and clicked the middle mouse button. |
| WM_RBUTTONDOWN | The user has placed the mouse cursor over the child window and clicked the right mouse button. |
wValue1
Value of the low-order word of lParam. If the fwEvent parameter is WM_CREATE or WM_DESTROY, the wValue1 parameter specifies the handle of the child window. Otherwise, wValue1 specifies the x-coordinate of the cursor.
wValue2
Value of the high-order word of lParam. If fwEvent is WM_CREATE or WM_DESTROY, the wValue2 parameter specifies the identifier of the child window. Otherwise, wValue2 specifies the y-coordinate of the cursor.
An application should return zero if it processes this message.
This message is also sent to all ancestor windows of the child window, including the top-level window.
All child windows except those that have the WS_EX_NOPARENTNOTIFY send this message to their parent windows. By default, child windows in a dialog box have the WS_EX_NOPARENTNOTIFY style unless the CreateWindowEx function was called to create the child window without this style.
CreateWindow, CreateWindowEx, WM_CREATE, WM_DESTROY, WM_LBUTTONDOWN, WM_MBUTTONDOWN, WM_RBUTTONDOWN