I want Webstorm to start with the files/tabs, which were open when I quit Webstorm the last time. Where do I find this setting? I'm using Webstorm 11.
Deleting the folder MYPROJECT/.idea solved my problem.
@LazyOne pointed out correctly, that WebStorm starts with the files from the last session by default. My configration files might have been corrupt because of a blue screen which occured yesterday.