1.  What is Caja ?

  Caja is an open-source file manager and graphical shell being
  developed by Eazel, Inc. and others. It is part of the MATE project, and its
  source code can be found in the MATE CVS repository. Caja is still in
  the early stages of development. It will become an integral part of the
  MATE desktop environment when it is finished.
