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
expressionProvider,
				this.bindingHolder );
	}
	public void validate( )
	{
		if ( txtName != null
				&& ( txtName.getText( ) == null || txtName.getText( )
						.trim( )
						.equals( "" ) ) ) 
		{
			dialog.setCanFinish( false );
		}
		else if ( txtExpression != null
				&& ( txtExpression.getText( ) == null || txtExpression.getText( )
						.trim( )
						.equals( "" ) ) ) 
		{
			dialog.setCanFinish( false );
		}
		else
		{
			if ( this.binding == null )
			
			{
				for ( Iterator iterator = this.bindingHolder.getColumnBindings( )
						.iterator( ); iterator.hasNext( ); )
				{
					ComputedColumnHandle computedColumn = (ComputedColumnHandle) iterator.next( );
					if ( computedColumn.getName( ).equals( txtName.getText( ) ) )
					{