[Lazarus] TTabControl has problem with storing/retreving objects

[Donald R. Ziesig]

  Hi All!

I have an app that uses a TTabControl to select the display of one of 
many objects.  The code is really trivial in the real app, but I have 
further simplified it to the bare essentials:

unit Unit1;

{$mode objfpc}{$H+}

interface

uses
   Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, 
StdCtrls,
   ComCtrls;

type

   { TForm1 }

   TForm1 = class(TForm)
     Button1: TButton;
     Label1: TLabel;
     TabControl1: TTabControl;
     procedure Button1Click(Sender: TObject);
     procedure TabControl1Change(Sender: TObject);
   private
     { private declarations }
     N : Integer;
   public
     { public declarations }
   end;

var
   Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
begin
   Inc(N);
   TabControl1.Tabs.AddObject(IntToStr(N),TObject(N));
end;

procedure TForm1.TabControl1Change(Sender: TObject);
var
   I : Integer;
begin
   I := TabControl1.TabIndex;
   Label1.Caption := IntToStr(Integer(TabControl1.Tabs.Objects[I]));
end;

end.

Pressing Button1 adds consecutively-numbered tabs starting at 1.
Selecting a tab SHOULD set Label1's caption to the number on the tab 
(and DOES when used with Delphi).  It actually outputs non-consecutive 
numbers in the 37,000,000 range.  I get similar results using Windows, 
OSX and Debian.

In the real app, I use an object with a name, but when I select a tab, 
it goes somewhere in the address space (not sure where in the context of 
the app) and returns a string of un-printable characters as the name 
(and other random values for the remaining contents of the object).

As I said above, the exact same code in Delphi (2006 and 2007) works as 
expected, but obviously is limited to Windows.

I tried similar operations with a TListBox and the object was returned 
correctly so I don't think the problem is with TStrings or its descendents.

Any help would be appreciated.

Don Ziesig

P.S.  I have tried to find the LCL code and debug the library myself but 
I must be missing something in my searches.  Some pointers in that area 
would also be appreciated.