Thanks a lot, Darwin - I am not sure I ever would have figured this out myself, because it quite frankly seems a little strange to do it this way only, not having the option to do it via the normal settings in View or Tools. Even more strange I think it is, that one must db-click on the name of the image file, but not on the picture itself, in order to see the image in a ext. viewer. If picture A is marked, and I db-click picture B, it will open picture A. I find this feature really odd.