#  This macro mimics the old brstr_switch command

#  first put the current displayed raster into the 'a' (editable) raster.
disprstr_put

#  next get a copy of the 'b' raster
disprstr_get b

#  next, move the copy of the old dirplay into the 'b' raster
brstr_create

#  now, place the current display into the 'a' raster.
disprstr_put
