slightly improved demo

out-of-view label plot also has an in-view label to explain what's going on

Author: dkogan

demo.py

@@ -78,6 +78,9 @@ def check_expected_error(what, f):
          ( np.array((5,),), np.array((2,),), np.array(("Seeing this is a bug!",),),
            dict(_with = 'labels',
                 tuplesize = 3)),
+         ( np.array((5,),), np.array((7,),), np.array(("This SHOULD be visible. Another label should be out-of-view, below the x-axis",),),
+           dict(_with = 'labels',
+                tuplesize = 3)),
          _set  = 'yrange [5:10]',
          unset = 'grid',
          wait  = True)