Acquire new image : in the "Preferences" dialog, you can enter a command line to launch a tool (xsane, xscanimage,...) to acquire a new image. The corresponding image will not be automatically added to the currently selected film, which will have to be updated manually.
Edit with "The GIMP" : The GIMP (or any other tool) can be used to edit the currently selected image. The exact command line can be specified in the "Preferences" dialog box.
Edit with "Electric Eyes" : Electric Eyes is another tool which can be used to edit the currently selected image. The exact command line can be specified in the "Preferences" dialog box.