This update enforces the following behaviors:

  1. When resoures are loaded via File->Open, ParaView semantics
  apply: the apply button must be pressed to complete opening the
  file. This matches the functionality of the other ParaView readers
  (that are selectable when there are multiple readers for a file
  type).

  2. When a resource is created via File->New Resource, a modal dialog
  is presented to the user. When the user presses apply on the dialog,
  the resource is generated and its representation is rendered. The
  Properties Panel's apply button is never enabled. NOTE: the original
  plan was to move the contents of the modal dialog to the Properties
  Panel. This worked, but it looked pretty bad and was not intuitive.

  3. When a resource is created by an operation from the Operation
  Panel, the resource is generated and its representation is
  rendered. The Properties Panel's apply button is never enabled.