[[escafandra]]

Echemos mano a la API:

Código Delphi [-]
Form2 := TFrm2.Create( Self );
Form2.Left:= 0;
Form2.Top:= 0;
Form2.Width:= Panel2.Width;
Form2.Height:= Panel2.Height;
Windows.SetParent(Form2.Handle, Panel2.Handle);
Form2.OnClose := AlCerrar;
Form2.Show;

Saludos.