Clarify that ``DataSource.selected`` is read-only
@@ -71,7 +71,9 @@ class DataSource(Model):
'''
selected = Instance(Selection, default=lambda: Selection(), readonly=True, help="""
- A Selection that indicates selected indices on this ``DataSource``.
+ An instance of a ``Selection`` that indicates selected indices on this ``DataSource``.
+ This is a read-only property. You may only change the attributes of this object
+ to change the selection (e.g., ``selected.indices``).
""")
@abstract
