The WM_ENTERSIZEMOVE message is sent one time to a window after it enters the moving or sizing modal loop. The window enters the moving or sizing modal loop when the user clicks the window's title bar or sizing border, or when the window passes the WM_SYSCOMMAND message to the DefWindowProc function and the wParam parameter of the message specifies the SC_MOVE or SC_SIZE value. The operation is complete when DefWindowProc returns.
The system sends the WM_ENTERSIZEMOVE message regardless of whether the dragging of full windows is enabled.
WM_ENTERSIZEMOVE
wParam = 0; // not used, must be zero
lParam = 0; // not used, must be zero
This message has no parameters.
An application should return zero if it processes this message.
Windows NT: Requires version 3.51 or later.
Windows: Requires Windows 95 or later.
Windows CE: Unsupported.
Header: Declared in winuser.h.
Windows Overview, Window Messages, DefWindowProc, WM_EXITSIZEMOVE, WM_SYSCOMMAND