An application can set the owner for a window by using the WinSetOwner function. Typically, after setting the owner, a window notifies the owner window of the new relationship by sending it a message.
The code fragment in the following figure shows how to set the owner window and send it a message:
#define NEW_OWNER 1
HWND hwndMyWindow;
HWND hwndNewOwner;
if (WinSetOwner(hwndMyWindow, hwndNewOwner))
/* Send a notification message. */
WinSendMsg(hwndNewOwner, /* Sends to owner */
WM_CONTROL, /* Control message for notification */
(MPARAM) NEW_OWNER, /* Notification code */
NULL); /* No extra data */
A window can have only one owner, so WinSetOwner removes any previous owner.