I reverted to 7 when 8 first came out in part because file associations in 8 were completely borked.
I’m now trying again to switch to 8 and I have similar problems. Most of my files still open in 7 even though I’ve configured 8 to take over the file associations.
I don’t want to uninstall 7 yet as I’m still wary of 8 (no noticeable improvements that I’ve seen and it’s just as slow as 7).
If the only answer is to uninstall 7 then shame on Activestate for leaving behind the old versions.
The file associations you configure in Komodo are only meant to associate extensions to languages, it does not make any associations on the OS level. To have certain files be opened by Komodo by default you would have to configure this on the OS level, eg. http://support.microsoft.com/kb/307859. Or use a tool like http://defaultprogramseditor.com/.
Ideally Komodo would provide a setting for this, but this is currently not the case, nor (to my knowledge) has it ever been.