BM_SETSTATE
wParam = (WPARAM) fState; /* highlight state */
lParam = 0; /* not used, must be zero */
An application sends a BM_SETSTATE message to change the highlight state of a button.
fState
Value of wParam. Specifies whether the button is to be highlighted. TRUE highlights the button. FALSE removes any highlighting.
The message always returns zero.
Highlighting affects the exterior of a button. It has no effect on the check state of a radio button or check box.
A button is automatically highlighted when the user presses and holds the left mouse button. The highlighting is removed when the user releases the mouse button.
BM_GETSTATE, BM_SETCHECK