Bug 390669 [Accessibility]Press 'Tab' doesn't focus on the next report item when adding relative period aggregation.
xtab/org.eclipse.birt.report.item.crosstab.ui/src/org/eclipse/birt/report/item/crosstab/internal/ui/dialogs/CrosstabBindingDialogHelper.java
}
			public void widgetSelected( SelectionEvent arg0 )
			{
				modifyDialogContent( );
				validate( );
			}
		} );
		if ( isTimePeriod( ) )
		{
			createCalculationSelection( composite );
		}
		
		if ( isAggregate( ) )
		{
			createAggregateSection( composite );
		}
		else
		{
			createCommonSection( composite );
		}
		if ( isTimePeriod( ) )
		{
			new Label( composite, SWT.NONE ).setText( Messages.getString( "CrosstabBindingDialogHelper.timedimension.label" ) ); 
			timeDimension = new Combo( composite, SWT.BORDER | SWT.READ_ONLY );
			timeDimension.setLayoutData( gd );
			timeDimension.setVisibleItemCount( 30 );
			timeDimension.addSelectionListener( new SelectionListener( ) {
				public void widgetDefaultSelected( SelectionEvent arg0 )
				{
					validate( );