The commands described in this reference page enable the user to sort the items of a tablelist widget based on one or more of its columns, with the aid of the left mouse button.
If the tablelist::sortByColumn command was specified
  as the value of the -labelcommand
  configuration option, then by pressing mouse button 1 over one of the header
  labels and later releasing it over the same label, the items will be sorted
  based on the elements of the corresponding column.
If the tablelist::addToSortColumns command was
  specified as the value of the -labelcommand2
  configuration option, then by pressing mouse button 1 together with the
  Shift key over one of the header labels and later releasing it
  over the same label, the corresponding column will be appended to the list of
  sort columns, or (if it was already contained in that list) the corresponding
  sort order will be toggled; in both cases, the items will be sorted based on
  the updated lists of sort columns and sort orders.
tablelist::sortByColumn Commandtablelist::sortByColumn - Sort the items of a tablelist
    widget based on one of its columnstablelist::sortByColumn pathName columnIndex
pathName
      based on the elements of the column specified by
      columnIndex.  This is done by invoking the
      sortbycolumn
      subcommand of the Tcl command associated with the given tablelist
      widget.  If the items were last sorted in increasing order, based on
      the same column given by columnIndex, and no
      subsequent invocation of the resetsortinfo
      subcommand was made, then the last argument passed to
      sortbycolumn will be -decreasing,
      otherwise -increasing.
      After sorting the items, the virtual event
      <<TablelistColumnSorted>> is
      generated.  The command returns the corresponding sort order, as
      decreasing or increasing.
If the specified column's -showlinenumbers
      option has been set to true, then the actions described above are not
      performed and the return value is an empty string.
tablelist::sortByColumn is usually specified as
      the value of the -labelcommand
      configuration option for a tablelist widget.
tablelist::addToSortColumns Commandtablelist::addToSortColumns - Add a column index to the
    list of sort columns and perform the multi-column sortingtablelist::addToSortColumns pathName columnIndex
columnIndex to the list of sort columns of the
      tablelist widget
      pathName and sorts the items based on the elements of
      the columns indicated by the modified list.  This is done by
      invoking the sortbycolumnlist
      subcommand of the Tcl command associated with the given tablelist
      widget.  The two arguments passed to
      sortbycolumnlist are built as follows: (a) if the
      given column index is already contained in the widget's list of sort
      columns (returned by the sortcolumnlist
      subcommand) then this list is left unchanged and the sort order list
      (returned by the sortorderlist
      subcommand) is updated by toggling its corresponding element from
      increasing to decreasing and
      vice-versa; (b) otherwise the column index is appended to the list of
      sort columns and the value increasing is appended to
      the list of sort orders.
      After sorting the items by passing the two updated lists to the
      sortbycolumnlist subcommand, the virtual event
      <<TablelistColumnsSorted>> (note the
      plural form!) is generated.  The command returns the new sort order
      corresponding to the given column, as decreasing or
      increasing.
If the specified column's -showlinenumbers
      option has been set to true, then the actions described above are not
      performed and the return value is an empty string.
tablelist::addToSortColumns is usually specified
      as the value of the -labelcommand2
      configuration option for a tablelist widget.