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
layout.marginWidth = layout.marginHeight = 0;
		layout.horizontalSpacing = 0;
		layout.numColumns = 2;
		dateSelecionContainer.setLayout( layout );
		dateText = new Text( dateSelecionContainer, SWT.BORDER | SWT.WRAP );
		dateText.addModifyListener( new ModifyListener( ) {
			public void modifyText( ModifyEvent e )
			{
				dateFormatLbl.setText( getDateHintText( ) );
				modifyDialogContent( );
				validate( );
			}
		} );
		dateText.addFocusListener( new FocusListener( ) {
			public void focusGained( FocusEvent e )
			{
				todayButton.setSelection( false );
				recentButton.setSelection( false );
				dateSelectionButton.setSelection( true );
				dateButtonSelection( true );
			}
			public void focusLost( FocusEvent e )
			{
			}
		} );
		
		gd = new GridData( GridData.FILL_HORIZONTAL ) ;
		gd.heightHint = dateText.computeSize( SWT.DEFAULT, SWT.DEFAULT ).y
				- dateText.getBorderWidth( )
				* 2;