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
.getDataType( ) ) ) );
			}
			catch ( BirtException e )
			{
				ExceptionUtil.handle( e );
			}
		}
		else
		{
			( (GridData) paramsComposite.getLayoutData( ) ).heightHint = 0;
			( (GridData) paramsComposite.getLayoutData( ) ).exclude = true;
			
		}
		composite.layout( true, true );
		setContentSize( composite );
	}
	private void createExpressionButton( final Composite parent,
			final Control control )
	{
		if ( expressionProvider == null )
		{
			if ( isAggregate( ) )
				expressionProvider = new CrosstabAggregationExpressionProvider( this.bindingHolder,
						this.binding );
			else
				expressionProvider = new CrosstabBindingExpressionProvider( this.bindingHolder,
						this.binding );
		}
		ExpressionButtonUtil.createExpressionButton( parent,
				control,