The button control responds to this message, if it has a style of BS_PUSHBUTTON, BS_CHECKBOX, BS_AUTOCHECKBOX, BS_RADIOBUTTON, BS_AUTORADIOBUTTON, BS_3STATE, or BS_AUTO3STATE, by displaying the button control in the appropriate highlight state and setting foldstate as appropriate.

If the style of the Button Control is BS_USERBUTTON, a WM_CONTROL (in Button Controls) message is sent to its owner with usnotifycode set to BN_PAINT and with flcontrolspec pointing to a USERBUTTON structure and sets foldstate as appropriate.