This message retrieves the ID of the default push-button control for a dialog box.
| Parameter | Description |
| wParam | Is not used. | |
| lParam | Is not used. |
The return value is a 32-bit value. The high-order word contains DC_HASDEFID if the default button exists; otherwise, it is NULL. The low-order word contains the ID of the default button if the high-order word contains DC_HASDEFID; otherwise, it is zero.