     type: 'cross'
     x: 'x'
     y: 'y'
-    size: 'small_size'
+    size: 'pixel_size'
     line_width: 'lw'
     line_color: 'colors'
   }

    type: 'x'
    x: 'x'
    y: 'y'
    size: 'small_size'
    fill_color: 'colors'
    fill_alpha: 'alpha'
    line_width: 'lw'

    y: 'y'
    line_width: 'lw'
    line_color: 'colors'
    radius: 0.5            # for some reason, radius is in pixels.
    radius_units: 'data'            # for some reason, radius is in pixels.
    start_angle: 0
    end_angle: 2
  }
