[ecfisa]

Hola mjjj.

Si lo que queres es un form sin bordes y sizeable, hacé lo siguiente:

type
   TForm1 = class(TForm)
   private
       procedure CreateParams(var Params: TCreateParams); override;
   public
end;
 
var
  Form1: TForm1;
  ...
implementation 
 
procedure TForm1.CreateParams(var Params: TCreateParams);
begin
   BorderStyle := bsNone;
   inherited;
   Params.ExStyle := Params.ExStyle or WS_EX_STATICEDGE;
   Params.Style := Params.Style or WS_SIZEBOX;
end;

Saludos.