* View directive (screenshots): Missing features
  * Add suport to "field" attribute (probably requires changes in Tryton
    client)
  * Add suport to empty forms in URL system (change in Tryton)
  * Add a way to define which record use:
    * with XML ID => easy to implement, but pretty less useful because normally
      there isn't records added from XML
    * spceifying an ID => easy to implement, but not generic
    * specifying a domain
  * Add a way to define a context/domain to be passed to view to force the
    value of some field (to force some "states" condition)
  * Only get the content of the tab (the form or the tree), whithout menu nor
    window menus and decorations
    * Add an attribute to force to get all the window
  * Allow to define the user (and password) to use for the screenshot