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
calculationParamsValueMap.put( name, cmbDataField.getText( ) );
				}
			} );
			calculationParamsMap.put( name, cmbDataField );
		}
		else
		{
			final Text txtParam = new Text( calculationComposite, SWT.BORDER
					| SWT.WRAP );
			initCalculationTextFild( txtParam, name );
			txtParam.addModifyListener( new ModifyListener( ) {
				public void modifyText( ModifyEvent e )
				{
					modifyDialogContent( );
					validate( );
					calculationParamsValueMap.put( name, txtParam.getText( ) );
				}
			} );
			GridData gridData = new GridData( SWT.FILL, SWT.FILL, true, false );
			
			
			gridData.heightHint = txtParam.computeSize( SWT.DEFAULT, SWT.DEFAULT ).y
					- txtParam.getBorderWidth( )
					* 2;
			txtParam.setLayoutData( gridData );
			createExpressionButton( calculationComposite, txtParam );
			calculationParamsMap.put( name, txtParam );
		}
	}
	private void initCalculationTextFild( Text txtParam, String name )