Overview Of Item Types
The sections below describe the various types of items supported
by canvas widgets. Each item type is characterized by two things:
first, the form of the create command used to create
instances of the type; and second, a set of configuration options
for items of that type, which may be used in the
create and itemconfigure widget commands.
Most items don't support indexing or selection or the commands
related to them, such as index and insert.
Where items do support these facilities, it is noted explicitly
in the descriptions below (at present, only text items provide