WM_PARENTNOTIFY
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, Windows sends the
message before any processing to destroy the window takes place.
WM_PARENTNOTIFY
fwEvent = LOWORD(wParam); // event flags
idChild = HIWORD(wParam); // identifier of child window
lValue = lParam; // child handle, or cursor
coordinates
Parameters
fwEvent
Value of the
low-order word of wParam. Specifies the event for which the parent is
being notified. This parameter can be one of the following values:
|
Value |
Meaning |
|
WM_CREATE |
The child
window is being created. |
|
WM_DESTROY |
The child
window is being destroyed. |
|
WM_LBUTTONDOWN |
The user
has placed the cursor over the child window and has clicked the left mouse
button. |
|
WM_MBUTTONDOWN |
The user
has placed the cursor over the child window and has clicked the middle mouse
button. |
|
WM_RBUTTONDOWN |
The user
has placed the cursor over the child window and has clicked the right mouse
button. |
idChild
Value of the
high-order word of wParam. If the fwEvent parameter is the
WM_CREATE or WM_DESTROY value, idChild specifies the identifier of the
child window. Otherwise, idChild is undefined.
lValue
Contains the
handle of the child window, if the fwEvent parameter is the WM_CREATE or
WM_DESTROY value; otherwise, lValue contains the x- and y-coordinates of
the cursor. The x-coordinate is in the low-order word and the y-coordinate is
in the high-order word.
Return Values
If an
application processes this message, it should return zero.
Remarks
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 extended window style,
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 is called to create the child window without this style.
See Also