Bug 124742 Disable/change fixed base value for string and date data
The Use fixed base value for interval option in the Edit Group dialog should be disabled for string and date data because it has no effect on these types of values. For date data, for example, if I specify a grouping interval of 1 week, and I specify a base value of 01/01/2006 (a Sunday), the dates are still grouped by weeks that start on Monday.
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/GroupDialog.java
/**
	 * The name editor
	 */
	private Text nameEditor;
	/**
	 * The group key and interval type combo box.
	 */
	private Combo keyChooser, intervalType;
	/**
	 * The spinner to choose interval range;
	 */
	private Spinner intervalRange;
	private FormPage filterPage, sortPage;
	/**
	 * The include check box and sorting direction radio box
	 */
	private Button includeHeader, includeFooter, ascending, descending;
	private Button intervalBaseButton;
	private Text intervalBaseText;
	private Text tocEditor;
	final private static IChoice[] intervalChoices = DesignEngine.getMetaDataDictionary( )
			.getChoiceSet( DesignChoiceConstants.CHOICE_INTERVAL )
			.getChoices( );
	final private static IChoice sortByAscending = DesignEngine.getMetaDataDictionary( )
			.getChoiceSet( DesignChoiceConstants.CHOICE_SORT_DIRECTION )
			.findChoice( DesignChoiceConstants.SORT_DIRECTION_ASC );
	final private static IChoice sortByDescending = DesignEngine.getMetaDataDictionary( )
			.getChoiceSet( DesignChoiceConstants.CHOICE_SORT_DIRECTION )
			.findChoice( DesignChoiceConstants.SORT_DIRECTION_DESC );
	final private static String SORT_GROUP_TITLE = DEUtil.getPropertyDefn( ReportDesignConstants.TABLE_GROUP_ELEMENT,