const Info = 100;
TrayIko = 101;

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public
{ Public declarations }
hSysMenu: hmenu;
procedure WMSysCommand(var Message: TMessage); message WM_SYSCOMMAND;
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procedure TForm1.WMSysCommand(var Message : TMessage);
begin
if Message.WParam = Info then ShowMessage('Kliknuto na položku Info');
if Message.WParam = TrayIko then ShowMessage('Kliknuto na položku Minimalizace do tray...');
inherited;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
hSysMenu := GetSystemMenu(Form1.Handle, False);
AppendMenu(hSysMenu, MF_SEPARATOR, 0, '');
AppendMenu(hSysMenu, MF_STRING, Info, '&Info');
AppendMenu(hSysMenu, MF_STRING, TrayIko, 'Minimalizuj do &hlavního panelu');
end;