I just upgraded the Version 10 of webGrid and this issue came back! Again you can see this using Firefox 47.x

You can see this using the FirstExperience vb sample. Change the height of the frist TD from 61px to 200px and then add ShowColumnAction="true" to LayoutSettings. Run the sample, move the scrollbar down and go to column header to view the column action button, note that its location is down in the grid. I've attached a screen shot. It appears to only work this way in Firefox, Chrome and IE11 display correct.

thanks

function getWebGridData() {            var WebGrid1 = wgGetGridById("WebGrid1");
            var totalRows = WebGrid1.TotalRows;
            var sb = '';  

            for (var i = 0; i < totalRows; i++) {
                sb += '{';
                var _Row = WebGrid1.RootTable.GetRow(i);
                var cells = _Row.GetCells();
                
                sb += '"DOT_NUMBER" : "' + cells.GetNamedItem('DOT').Value + '", "PHY_LAT" : "' + cells.GetNamedItem("pLat").Value + '", "PHY_LONG" : "' + cells.GetNamedItem("pLong").Value + '", "TYPE" : "' + cells.GetNamedItem("AuditTypeDesc").Value + '"' ;
                sb += '},';
            }
            sb = sb.substring(0, sb.length - 1);
            //alert(sb);
            return sb;
        }

thanks