Returns the main control of a preference, which is mainly used to 
	     * manage the focus. This may be <code>null</code> if the preference doesn't
	     * have a control which is able to have the focus.
Returns the main control of a preference, which is mainly used to 
	     * manage the focus. This may be <code>null</code> if the preference doesn't
	     * have a control which is able to have the focus. | ModifyDialogTabPage.java