procedure TForm1.FormCloseQuery(Sender: TObject; var CanClose: Boolean);
begin
case Application.MessageBox('确定退出系统？','询问',35) of
6:
begin
ShowMessage('按了是，窗口关闭');
CanClose:=True;
end;
7:
begin
ShowMessage('按了否，返回登陆窗口');
CanClose:=True;
//这里写上你的登陆窗口调用代码
ShowMessage('登陆窗口出现了');
end;
2:
begin
ShowMessage('按了取消，窗口不关闭');
CanClose:=False;
end;
end;
end;
