The 'context-insensitive' code completion 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