procedure TForm1.Button1Click(Sender: TObject);
var
F: TForm;
B: TButton;
begin
F := TForm.Create(Application);
begin
B := TButton.Create(F);
B.Parent := F;
B.Left := 100;
B.Top := 100;
B.OnClick := Button1Click;
F.Left := Random(500);
F.Top := Random(500);
F.Show; // или F.ShowModal;
end;
end;