ENH: Enables specification of PDF Weight for forground and background.

Also removes nonexistant FPR Weight parameter.
Change-Id: I0a18d1bfe96e5895832c76982753d998d7fb0c8f
ENH: Enables popup slider boxes to adjust the object weights.

Change-Id: I41d1f623bc33445d7e296a8c2552f332baced39b