求教，以下代码为啥挂起了？

冥界3大法王

[Delphi] 纯文本查看 复制代码

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants,
  System.Classes, Vcl.Graphics, Vcl.Controls, Vcl.Forms, Vcl.Dialogs;

type
  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
    procedure sysmenu(var msg: twmmenuselect); message wm_syscommand;
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
var
  i: integer;
begin
  i := getsystemmenu(handle, false);
  appendmenu(i, mf_separator, 0, nil);
  appendmenu(i, mf_string, 100, '窗口置顶');
end;

procedure TForm1.sysmenu(var msg: twmmenuselect);
begin
  if msg.IDItem = 100 then
    SetWindowPos(Form1.Handle, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE or SWP_NOSIZE)
  else
    SetWindowPos(Form1.Handle, HWND_NOTOPMOST, 0, 0, 0, 0, SWP_NOMOVE or SWP_NOSIZE);
end;

end.

bookaccount

参考 https://stackoverflow.com/questi ... -using-setwindowpos

冥界3大法王

明白了，
procedure TForm1.sysmenu(var msg: TWMMenuSelect);
begin
  if msg.IDItem = 100 then
    SetWindowPos(Form1.Handle, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE or SWP_NOSIZE)
  else
    inherited;


  if msg.IDItem = 101 then
    SetWindowPos(Form1.Handle, HWND_NOTOPMOST, 0, 0, 0, 0, SWP_NOMOVE or SWP_NOSIZE)
  else
    inherited;
end;