{
 Suppose you have a TListBox containing some date values.
 If you want to sort the dates by setting the "Sorted"
 property to "True" you will see that the dates are not sorted correctly:
 12.03.2003
 13.03.2003
 29.01.2003
 30.03.2003
 Now what you can do is to is create a TStringlist, Assign the listbox.Items
 property to it, sort the stringlist using CustomSort,
 then Assign it back to listbox.items.
}

 function CompareDates(List: TStringList; Index1, Index2: Integer): Integer;
 var
  d1, d2: TDateTime;
 begin
  d1 := StrToDate(List[Index1]);
  d2 := StrToDate(List[Index2]);
  if d1 < d2 then
  Result := -1
  else if d1 > d2 then Result := 1
  else
  Result := 0;
 end;
 procedure TForm1.Button1Click(Sender: TObject);
 var
  sl: TStringList;
 begin
  sl := TStringList.Create;
  try
  // listbox1.Sorted := False !
  sl.Assign(listbox1.Items);
  sl.CustomSort(CompareDates);
  listbox1.Items.Assign(sl);
  finally
  sl.Free
  end;
 end;
 end.

 {********************************************************************}
 { To sort Integer values:}
 function CompareInt(List: TStringList; Index1, Index2: Integer): Integer;
 var
  d1, d2: Integer;
  r1, r2: Boolean;
  function IsInt(AString : string; var AInteger : Integer): Boolean;
  var
  Code: Integer;
  begin
  Val(AString, AInteger, Code);
  Result := (Code = 0);
  end;
 begin
  r1 := IsInt(List[Index1], d1);
  r2 := IsInt(List[Index2], d2);
  Result := ord(r1 or r2);
  if Result <> 0 then
  begin
  if d1 < d2 then
  Result := -1
  else if d1 > d2 then
  Result := 1
  else
  Result := 0;
  end else
  Result := lstrcmp(PChar(List[Index1]), PChar(List[Index2]));
 end;
 procedure TForm1.Button1Click(Sender: TObject);
 var
  sl: TStringList;
 begin
  sl := TStringList.Create;
  try
  // listbox1.Sorted := False;
  sl.Assign(listbox1.Items);
  sl.CustomSort(CompareInt);
  listbox1.Items.Assign(sl);
  finally
  sl.Free;
  end;
 end;