procedure TForm1.Button2Click(Sender: TObject);
var
   C : TControl;
   E : TEdit;
   I : Integer;
   RB : TRadioButton;
begin
   E := TEdit.Create(nil);
   E.Parent := self;
   window.alert('added TEdit');
   for I := 0 to ControlCount - 1 do begin
      if Controls[I] is TEdit then begin
         C := Controls[I];
         C.Free;
      end;
   end;
   window.alert('freed TEdit');
   RB := TRadioButton.Create(nil);
   RB.Parent := self;
   window.alert('added TRadioButton');
   for I := 0 to ControlCount - 1 do begin
      if Controls[I] is TRadioButton then begin
         C := Controls[I];
         C.Free;
      end;
   end;
   window.alert('freed TRadioButton');
end;