That's very interesting. I don't send the image to the image viewer, but actually, I send the image to the application that's registered to open images, and it's usually image-viewer. I guess Opera also registers itself to open images and that's why you get both. Since this is a test I'm still not sure what I'm gonna do later in Yappari, but the idea I like the most is image-viewer "forced" (no matter what you have registered) and browser as an option in the Settings dialog (Yapari will have a Settings dialog).