(Owner as TForm).Handle cause invalid type cast error

[guscottg]

I'm have Delphi 6 with all patches applied. I'm using the following code which I've taken from the Delphi 4 Unleashed book:

procedure TChildFrm.CreateParams(var Params: TCreateParams);
begin
inherited CreateParams(Params);
Params.WndParent := (Owner as TForm).Handle;
Params.Style := WS_CHILD or WS_CLIPSIBLINGS;
Params.X := 0;
Params.Y := 0;
end;

When I compile my application I receive the following error:

"Exception EInvalidCast in module xxxx at xxxxx. Invalid class subtype."

What I'm trying to do is to display a form inside a container like a TPageControl or a TPanel.

 

[whosrdaddy]

the exception you are getting is normal because the owner is not a form but a tpanel or Tpagecontrol.

to create a window inside a panel you can do this :

 formx:=TFormx.Create(Panel1);
 formx.ParentWindow:=Panel1.Handle;
 formx.Show;

or change the code in your CreateParams procedure like this :

Params.WndParent := (Owner as TWinControl).Handle;

cheers

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