GUI.CreateButton[Full]

GUI.CreateButtonFull (x, y, width : int, text : string,
    actionProc : procedure x (), height : int, shortcut : char, default : boolean) : int

The button widget is used to implement a textual button. When you click on a button, the button's action procedure is called. If a button is given a short cut, then entering the keystroke will cause the action procedure to be called. It will not visibly cause the button to depress.

The x and y parameters specify the lower-left corner of the button. The width parameter specifies the width of the button. If width is less than the size necessary to display the button, the button is automatically enlarged to fit the text. The text parameter specifies the text to appear in the button. The actionProc parameter is the name of a procedure that is called when the button is pressed.

For GUI.CreateButtonFull, the height parameter specifies the height of the button. If height is less than the size necessary to display the button, the button is automatically enlarged to fit the text. The shortcut parameter is the keystroke to be used as the button's shortcut. The default parameter is a boolean indicating whether the button should be the default button. If there is already a default button, and default is set to true, then this button becomes the new default button.

        import GUI
        
        procedure DrawRandomCircle
            var r : int := Rand.Int (20, 50)
            var x : int := Rand.Int (r, maxx - r)
            var y : int := Rand.Int (r, maxy - r)
            var c : int := Rand.Int (0, maxcolor)
            Draw.FillOval (x, y, r, r, c)
            % In case we drew over the buttons, redraw them.
            GUI.Refresh
        end DrawRandomCircle
        
        View.Set ("graphics:300;200,nobuttonbar ")
        var draw : int := GUI.CreateButtonFull (50, 10, 0, "Draw Circle",
            DrawRandomCircle, 0, '^D', true)
        var quitBtn : int := GUI.CreateButton (200, 10, 0, "Quit", GUI.Quit)
        loop
            exit when GUI.ProcessEvent
        end loop

If a button's width or height is set to zero (or not specified at all), then the button is shaped to fit the text.

A button can be the default button for a window. The default button is drawn with a thicker border around it. If the user presses ENTER in a window with a default button, the default button's action procedure is called.

When a button is not enabled, the text in the button is grayed out and the button no longer responds to any mouse clicks or keystrokes until the button is enabled again.

This means that you can only call the function by calling GUI.CreateButton, not by calling CreateButton.