Hi Stefan, it sounds like you've got it figured out now?

I think this is controlled in OSX by doing a right-click on the file and then picking the "Open with" menu, if you go to the dialog chooser there you can pick an app for the file type and then there is a checkbox to always open with that app.

I guess that's the UI for Lion and newer, for Snow Leopard right click and choose "Get info" and then the control for which app to use for that file type is on the info pane.

- Michael

Hi Michael,

yes, i figured it out under Snow Leopard. First i did the "Open with" method which did not worked and then i choose the "Get Info" dialog, which works.

Best regards
Stefan

On a side note, one can also change the meaningless blank paper sheet icon of MoI's .3dm files using this procedure:
http://support.apple.com/kb/HT2493

I copied the MoI app icon and all .3dm files show the bulb now. Much better!

Thanks for the tip!

Regards
Stefan