Buttons are window controls that are, at any time, in one of two basic states: selected or not selected. Depending on the button’s type and purpose, the selected state may be referred to as DOWN, ON or CHECKED, and the unselected state as UP, OFF or UNCHECKED. They normally have a brief label, which appears on the button to indicate the effect of pressing it:


The dialog and input commands allow the operator to change the state of a button or group of buttons. Additionally, run time commands may be used to change the properties of a button without the user being involved in, or necessarily aware of, the operation.

Each button is declared as a clause of the window in which it appears, using the form:

+|–button button_id at x, y {