Patrick,

>I'm still in the jump starts and having a problem in my Web Forms Application. I want to go into design mode (f.ex. of the MasterPageMain.master), but there is no "Design" and "Source" option below. When forcing the design mode with the referent button I get "There is no editor available for "....MasterPageMain.master". Make sure the application for the file type (.master) is installed."

Are you double-clicking on the master page to display it in design mode? Which version of Visual Studio are you using? I recommend adding a regular master page to your application to see if you can open it.

Best Regards,