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
gd.widthHint = width;
					lblParam.setLayoutData( gd );
					if ( param.isDataField( ) )
					{
						final Combo cmbDataField = new Combo( paramsComposite,
								SWT.BORDER );
						cmbDataField.setLayoutData( GridDataFactory.fillDefaults( )
								.grab( true, false )
								.span( 3, 1 )
								.create( ) );
						cmbDataField.setVisibleItemCount( 30 );
						initDataFields( cmbDataField, param );
						cmbDataField.addModifyListener( new ModifyListener( ) {
							public void modifyText( ModifyEvent e )
							{
								modifyDialogContent( );
								validate( );
								paramsValueMap.put( param.getName( ),
										cmbDataField.getText( ) );
							}
						} );
						paramsMap.put( param.getName( ), cmbDataField );
					}
					else
					{
						final Text txtParam = new Text( paramsComposite,
								SWT.BORDER | SWT.WRAP );
						initTextField( txtParam, param );
						txtParam.addModifyListener( new ModifyListener( ) {
							public void modifyText( ModifyEvent e )