>>Think you'll have to dig in the registry to find the open command
>>
>>(1) under HKEY_CLASSES_ROOT look for dot + extension
>>
>>eg pdf becomes .pdf
>>
>>The (default) on the right gives you the name of the application
>>
>>(2) under HKEY_CLASSES_ROOT\nameOfApplication\Shell\Open\Command you will find the command line
>>
>>See attached example
>
>Thanks, I'll go this route, but it's quite inconvenient, don't you think? I remember it used to be available to see and change directly from the Windows File Extensions dialog.

You can rightclick a file, take Open with, then you can choose a program and if you want set it as the default program