Author: Tomas Rutkauskas 

Is it possible to free a component inside its own event handler?

Answer:

Not safely. You never know what the code after your free statement will still try 
to do with the (now invalid) self reference.

Do it the way forms implement the Release method: post a user message to the form, 
passing the control to delete as parameter, then free the control in the message 
handler:


1   const
2     UM_DELETEOBJECT = WM_USER + 666;
3   type
4     TUMDeleteObject = packed record
5       Msg: Cardinal;
6       Obj: TObject;
7       Unused: Longint;
8       Result: Longint;
9     end;
10  
11    {in form declaration, private section}
12  
13  procedure UMDeleteObject(var msg: TUMDeleteObject); message UM_DELETEOBJECT;
14  
15  procedure TaaDEOutputFrm.UMDeleteObject(var msg: TUMDeleteObject);
16  begin
17    msg.Obj.Free;
18  end;
19  
20  procedure TaaDEOutputFrm.PanelClick(Sender: TObject);
21  begin
22    if Sender is TPanel then
23      PostMessage(handle, UM_DELETEOBJECT, wparam(sender), 0);
24  end;