The 'group' property

An integer in the range 0 to 255

Valid for: Menu, Radio, ToolButton

Menu items

The group property is used to make Menu items behave like radio buttons. It indicates which group of mutually-exclusive menu buttons the object belongs to. When one item in the group is selected (by the user or under program control), all others in the same group on the same menu are de-selected. The group property is an arbitrary number in the range 0 to 255 which serves to identify the group within the window. If the value is 0, the control does not exhibit radio-button behavior.

Radio buttons

The group property of a Radio button determines which group (within a particular control) the button belongs to. Only one Radio button in the group can be selected at any time, so that if one is selected, all others in the same group are automatically de-selected.

Usually, this grouping occurs automatically (typically, you place Radio buttons in a Frame object). The initial group property for the first Radio button to be created as the child of a Frame or Window is 0. If you create further Radio buttons one after another with the same parent, the group property for each new button is the same as that of the previous button, so each button in the series belongs to the same group.

If you create a different control or controls in between, the group property is incremented by one for the next series, so that the second series of Radio buttons behaves independently of the first.

Alternatively, you can override this behavior and set the Radio button's group explicitly, as an integer scalar in the range 0 to 255.

ToolButtons

For a ToolButton, the group property determines which group of similar buttons the control belongs to, and thus whether it behaves like a readio button. If it is 0, the button behaves like an Action button. See the description of the ToolButton for details.