Sales Order Details Page Modification

Dear All.

I have do some modification on the Sales Order Detail.

I have created an combobox which change then fire selectionChange event, then will execute the ds.executeQuery() function.

But as the result I found that after the executeQuery finish. then record will no stay to my current record but the last record created. So how can I write the code to let my selectionChange event to stay on same record?

Thank you for advance