Bug 122177 Add input for IntervalBase to Group Editor
BIRT model's group definition has one important property: IntervalBase (see GroupHandle.setIntervalBase). This property controls how interval-based grouping picks the range of its initial group, and is an important part of range-based grouping. BIRT designer's Group Details editor should allow user to edit IntervalBase for a group. This is how the editor should work: * IntervalBase options should be presented only if "Interval" is not "None". (Since IntervalBase only makes sense for interval-based grouping) * IntervalBase should be presented in conjunction with checkbox. When it is unchecked (maps to a NULL IntervalBase value), Data Engine dynamically picks a base value using the first group key value in the result set. When it is checked, the user should input a base value. The following is a suggested look of the UI control: [ ] Use fixed base value for interval: _______________ ( [] is a checkbox, underline ___ is a textbox ).
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/ui/dialogs/GroupDialog.java
* 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 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,
			GroupHandle.SORT_DIRECTION_PROP )
			.getDisplayName( );
	/**
	 * Constructor.
	 * 
	 * @param parentShell
	 */