Under windows (at least 7, which is what I have on my editing machine), you can drag and drop image files, but not images that appear within apps. Your post led me to try something. In windows, the association between data files and executables is held in the file extension, not the file fork used in the mac OS, and you can change the association at will, but you can only specify one association per extension. I have jpegs associated with irfanview. So, I created shortcuts on my desktop for both irfanview and photoshop and dragged a jped file over to them. In the case of irfanview, it just opened. In the case of PS, it asked me what to do and then opened it when I requested that action.