Thanks Bryon,
I tried the RegServer solution and this does not seem to work for me. I believe based upon the reading, this has more to do with multiple installations of Arbortext on the same machine (telling Windows which is the current copy).
My issue has more to do with the way WIndows opens Arbortext when you double-click am xml file (when Arbortext is not already open).
I recall in the past, If I install Arbortext Editor only first, the Windows association is setup. Then if I modify the installation to add styler, the association is not affected and thus works that way I want.
I was just hoping there was an easier way to force the association to open editor rather than styler.
Thanks for the suggestion