Display completer if no matches, but do not activate any of the options

[krassowski]

The problem

When continuous hinting is enabled, one could stumble upon a completer showing up with all potential suggestions if not match is available; if this happens at the end of a line this poses a problem with the current completer implementation, as the first options is always activated when completer is displayed and this means that hitting Enter with an intent to insert new line will actually select the first completion suggestion (see #334).

How is it done today, and what are the limits of current practice?

This is currently worked around by not showing completer at all in such cases (#335).

Proposed solution

Preferably we would show the completer in all cases, but if there is no suggestion match the we would not activate any completion item (thus avoiding the problem).

How much will it cost?

We probably need a PR into the core to make it happen, and we need to propose a reasonable adjustment in the interfaces first. We probably want this as an optional argument to the trigger action.

Btw, exposing activeItemChanged signal would be useful too!