The 'context-insensitive' code completion is only available with the 'Pydev Extensions' plugin. It brings up completions with tokens found it the pythonpath and automatically imports the module that contains that token when selected.

It is shown only when the completion is requested for the globals and 3 characteres are already typed.

NOTE: You need to request the completions to show with Ctrl+Space

Image: All the tokens that start with 'xml' in the pythonpath

Image: Result of selecting the 'XMLFilterBase' token