Issue #2177335 by drintios, idebr, czigor, oo0shiny, bdimaggio, samiullah,...

          // Make our new row and select field.

          var row = $(this).closest('tr');

          var select = $(this);

          // Find the correct region and insert the row as the last in the

          // region.

          table.find('.region-' + select[0].value + '-message').nextUntil('.region-message').eq(-1).before(row);

          tableDrag.rowObject = new tableDrag.row(row[0]);

          var region_message = table.find('.region-' + select[0].value + '-message');

          var region_items = region_message.nextUntil('.region-message, .region-title');

          if (region_items.length) {

            region_items.last().after(row);

          }

          // We found that region_message is the last row.

          else {

            region_message.after(row);

          }

          updateBlockWeights(table, select[0].value);

          // Modify empty regions with added or removed fields.

          checkEmptyRegions(table, row);

          checkEmptyRegions(table, tableDrag.rowObject);

          // Update last placed block indication.

          updateLastPlaced(table, row);

          // Show unsaved changes warning.