I have diligently searched everywhere:- both the internet and the forums. Even as I ask this question the software attempts to block it and misinterpret my issue. Every response gets confounded into describing the use of default programs. This fails to solve the problem, since its scope is restricted to ALREADY INSTALLED file types. There have been many who have asked, but all answers were not adequate. One reply from a Microsoft person did admit that use of Default Programs does not allow creation of new file types. So I am left with this question: how may i test my application, including testing its behavior with new file types. I do not know enough about the registry to attempt to manually install a new file type, and even if I did, I would probably write AND TEST a program to do it safely and reliably. Under W7, I did create and save a file with an extension which did not appear under HKEY_CLASSES_ROOT\SOFTWARE\Classes hoping it would get added to the list under defaults. But when I checked later, it had not appeared. (I have not rebooted yet.) Earlier versions of Windows allowed new types with differing amounts of ease, but Windows 7 seemingly does not. The only thing I can thing of is to accept your offer of a way to restore all the defaults, and try to hack it so as to add my wanted new extensions to the list. But if I do that, I lose the extensions for whatever other software I may have installed. It is a quandry. I do hope that I am being stupid and missing something obvious (along with many others). If so, I'll happily eat crow in order to get on with testing. Although you probably do not need it, the email is dbd400@gmail.com. Thanks for any aid possible in this. dbd

if you are creating an app that say, opens a .new file windows will automatically add it to the registry. Otherwise check your policies. or you may need to enter the thing to the registry manually to fileassociations hives. But before you can do that, you'll have to make sure your new application is properly installed. Perhaps you can try setting the notepad to open your .new file, if it can be associated to a notepad then you can say that you still need to do something with the installation of your app. http://www.cesabarre.com/