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
}
	/**
	 * Creates the field area
	 * 
	 * @param parent
	 *            the parent composite
	 */
	private void createFieldArea( Composite parent )
	{
		Composite composite = new Composite( parent, SWT.NONE );
		composite.setLayout( new GridLayout( ) );
		GridData gd = new GridData( GridData.FILL_BOTH );
		gd.widthHint = 200;
		composite.setLayoutData( gd );
		
		new Label( composite, SWT.NONE ).setText( GROUP_DLG_GROUP_NAME_LABEL );
		
		nameEditor = new Text( composite, SWT.SINGLE | SWT.BORDER );
		nameEditor.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		
		new Label( composite, SWT.NONE ).setText( GROUP_DLG_GROUP_KEY_LABEL );
		
		Composite keyArea = new Composite( composite, SWT.NONE );
		keyArea.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		keyArea.setLayout( UIUtil.createGridLayoutWithoutMargin( 2, false ) );
		keyChooser = new Combo( keyArea, SWT.DROP_DOWN );
		keyChooser.setLayoutData( new GridData( GridData.FILL_HORIZONTAL ) );
		Button exprButton = new Button( keyArea, SWT.PUSH );
		exprButton.setText( "..." ); 
		exprButton.addSelectionListener( new SelectionAdapter( ) {