In WooCommerce admin view for categories/attributes we have on the right side in the table a draggable sort handler with the CSS class ui-sortable-handle. Both views, for the categories and attributes, are actually handled in WC_Admin_Taxonomies (class-wc-admin-taxonomies.php).

In the method product_cat_column() one can see that an input field is added to the column 'handle'. WC_Admin_Taxonomies leverages WP_List_Table, in there is a method single_row_columns() where classes are being added, but no trace from ui-sortable-handle.

Looking for ui-sortable-handle directly in hope to find a JQuery call adding this to the column also didn't show anything.

<td class="handle column-handle ui-sortable-handle" data-colname="" style="display: table-cell;"><input type="hidden" name="term_id" value="15"></td>

• Where is the class ui-sortable-handle added to the td tag in the table?
  
• Where is the 'missing link' in my research?

Thanks!