/**
     * Clears the selection such that none of the buttons 
     * in the <code>ButtonGroup</code> are selected.
     * 
     * @since 1.6       
     */ 
    public void clearSelection() {
        if (selection != null) {
            ButtonModel oldSelection = selection;
            selection = null;
            oldSelection.setSelected(false);            
        }
    }
 
    /**
     * Returns all the buttons that are participating in
     * this group.
     * @return an <code>Enumeration</code> of the buttons in this group
     */
    public Enumeration<AbstractButton> getElements() {
        return buttons.elements();
    }

    /**
     * Returns the model of the selected button.
     * @return the selected button model
     */
    public ButtonModel getSelection() {
        return selection;
    }

    /**
     * Sets the selected value for the <code>ButtonModel</code>.
     * Only one button in the group may be selected at a time.
     * @param m the <code>ButtonModel</code>
     * @param b <code>true</code> if this button is to be
     *   selected, otherwise <code>false</code>
     */
    public void setSelected(ButtonModel m, boolean b) {
        if (b && m != null && m != selection) {
            ButtonModel oldSelection = selection;
            selection = m;
            if (oldSelection != null) {
                oldSelection.setSelected(false);
            }
            m.setSelected(true);
        } 
    }

    /**
     * Returns whether a <code>ButtonModel</code> is selected.
     * @return <code>true</code> if the button is selected,
     *   otherwise returns <code>false</code>
     */
    public boolean isSelected(ButtonModel m) {
        return (m == selection);
    }

    /**
     * Returns the number of buttons in the group.
     * @return the button count
     * @since 1.3
     */
    public int getButtonCount() {
	if (buttons == null) {
	    return 0;
	} else {
	    return buttons.size();
	}
    }

}