A parent window can send messages to a button in an overlapped or child window by using the SendMessage function, or it can send messages to a button in a dialog box by using the SendDlgItemMessage, CheckDlgButton, CheckRadioButton, and IsDlgButtonChecked functions.
An application can use the BM_GETCHECK message to retrieve the check state of check box or radio button. An application can also use the BM_GETSTATE message to retrieve the button's current states (the check state, push state, and focus state). To get information about a specific state, use a bitmask on the returned state value.
The BM_SETCHECK message sets the check state of a check box or radio button; the message returns zero. The BM_SETSTATE message sets the push state of a button; this message also returns zero. The BM_SETSTYLE message changes the style of a button. It is designed for changing button styles within a type (for example, changing a check box to an automatic check box). It is not designed for changing between types (for example, changing a check box to a radio button). An application should not change a button from one type to another.
A button of the BS_BITMAP or BS_ICON style displays a bitmap or icon instead of text. The BM_SETIMAGE message associates the handle of a bitmap or icon with a button. The BM_GETIMAGE message retrieves the handle of the bitmap or icon associated with a button.
An application can also use the DM_GETDEFID message to retrieve the identifier of the default push button control in a dialog box. An application can use the DM_SETDEFID message to set the default push button for a dialog box.
Calling the CheckDlgButton or CheckRadioButton function is equivalent to sending a BM_SETCHECK message. Calling the IsDlgButtonChecked function is equivalent to sending a BM_GETCHECK message.
