运行通过，子窗口代码如下：
unit Unit2;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm2 = class(TForm)
private
{ Private declarations }
protected
procedure CreateParams(var Params: TCreateParams); override;
public
{ Public declarations }
end;
var
Form2: TForm2;
implementation
{$R *.dfm}
{ TForm2 }
{ TForm2 }
procedure TForm2.CreateParams(var Params: TCreateParams);
begin
inherited;
Params.ExStyle := Params.ExStyle or WS_EX_APPWINDOW;
end;
end.
