Hello ,

Below there is a implementation of the suggestion: 

<ClientSideEvents BeforeColumnSizeChangeHandler="UltraWebGrid1_BeforeColumnSizeChangeHandler" />

        function UltraWebGrid1_BeforeColumnSizeChangeHandler(gridName, columnId, width) {

            //Add code to handle your event here.

            if ((width < 300) && (igtbl_getColumnById(columnId).Key == 'ID')) {

                return true;

            }

        }