Idle Help, Completion sections "Two tabs in a row will supply the current ACW selection, as will return or a double click." On 3.4 windows, tab-tab works, one click dismisses the box immediately but without disabling it. Contrary to the claim above, <return> dismisses the box with no entry and enters <return> into the window (shell or editor). <space> on the other hand, does the same as tab-tab + enters a space. I actually like this better than return, but the doc and behavior should match and the widget never become disabled. The doc does not say anything about navigation.

I recently committed an *incomplete* test_autocomplete from one of last summer's GSOC students, but it obviously does not test what really needs to be tested.