Issue I426 [fly2,enhancement,resolved] In FLY2, new "window" standard_beam attribute. "window" works just like "pupil" except the particle velocity is in the opposite direction. As an example, define the source as a spherical distribution and the window as a point in the center of the sphere. The particles will start on the sphere and move normal to the sphere surface (in on the convex side) rather than toward the sphere center (as in the pupil type). Added in 8.0.4-TEST10.