*
* Note that you may get many calls @update_header to this for a particular row when e.g.
* changing things that don’t affect the header. In this case it is important for performance
- * to not blindly replace an exisiting header widh an identical one.
+ * to not blindly replace an existing header with an identical one.
*
* The @update_header function will be called for each row after the call, and it will
* continue to be called each time a row changes (via gtk_list_box_row_changed()) and when