Thank a lot, that works just fine!!!
An other question: is it possible to say in which window the url must be opened?
I have an application where you have to logon. When the user is logged on and a receives an email with an url to the application, he can click on the url and then, when the url is opened in the right window he can start working. When the url is opened in the wrong window or in a new window, he has to logon again.