Changes to a Button State

When the user selects a button, it is generally necessary to change one or more of the button's state elements. The system automatically changes the focus state for all button types, the push state for push buttons or buttons with the BS_PUSHLIKE style, and the check state for all automatic buttons. The application must make all other state changes, taking into account the button's type, style, and current state. The following list shows the state elements that must be changed for each button type:

• A check box must change the check state.
• A radio button must change the check state. It may also be necessary to change the check state of other radio buttons in the same group to ensure the mutually exclusive nature of radio buttons.
• Because the state of an owner-drawn button is application dependent, what the application must change in the button can vary. No elements of a group box must be changed, because users cannot select group boxes.

An application can determine a button's state by sending it a BM_GETCHECK or BM_GETSTATE message; the application can set a button's state by sending it a BM_SETCHECK or BM_SETSTATE message.