Seems to happen in all cases were Firefox wants to Display a error message in based on a xml message. In my case it mentioned it, when the page isn't reachable or some kind of 40x error happens or a certificate warning should be displayed.
Seems to happen in all cases were Firefox wants to Display a error message in based on a xml message. In my case it mentioned it, when the page isn't reachable or some kind of 40x error happens or a certificate warning should be displayed.