Why do Opera and all Chrome-based browsers not have the option to open PDF files with the default system application? In my case, it is Acrobat, but it could be any app. I often need to rearrange the pages before saving or printing the PDF file and the built-in readers do not allow editing of the file. It would be very helpful if Chrome-based browsers would allow choosing default system apps for all file types. If Opera and all Chrome-based browsers added this option I would drop Firefox as my default browser, but Firefox is the only browser that allows default apps.