This code specifies that the user has clicked a button. The parent window receives the code through a WM_COMMAND message from a button control.
| Parameter | Description |
| wParam | Specifies the control ID. | |
| lParam | Contains a handle that identifies the button control in its low-order word and the BN_CLICKED notification code in its high-order word. |
Disabled buttons will not send a BN_CLICKED notification message to a parent window.