Todd Kopriva posts the scripting changes that were made in After Effects CS6, as well as the new After Effects scripting guide. Todd also notes and itemizes what has changed from After Effects CS5.5 to After Effects CS6

a partial list of added scripting changes include: (for a complete list refer to the post or the After Effects CS6 scripting guide here.)

  • Added Viewer object. It represents a Composition, Layer, or Footage panel (viewer).
  • The canSetExpression attribute for the Property object now returns true for arbitrary data properties (like the Level effect’s Histogram property or the Curves effect’s Curves property) that could already accept expressions.
  • Added activeViewer attribute to the Application object. It gets the Viewer object for the currently focused or last-focused viewer. Returns null if no viewers are open.
  • Added environmentLayer attribute to the AVLayer object. It represents the environment layer status for a layer based on video footage or still image in a ray-traced 3D composition. You can set and get this Boolean value. Setting it to true automatically makes the layer 3D (threeDLayer becomes true).
  • Added openInViewer method to AVLayer object. It opens the AV layer in a Layer viewer, and moves the viewer to front and gives it focus. This method takes no parameters and returns a Viewer object, or null if it failed to open the viewer for some reason (e.g., for text or shape layers, which cannot open in the Layer viewer).