Advance to next blank grid row

We have custom modifications to Sales Order Entry. In the pristine version, if you select a sales order by clicking on the order number it opens the sales order and the cursor is positioned on the next blank row.  I am not sure if the last event called was grid so lines, row exited and changed asynch or not.

Due to our modifications, the cursor is positioned on the last grid row entered. How do I advance it to the next grid row? I think the last event called is a custom button we call from so grid lines, row exit and changed asynch, then our custom button.