InfoWindow support / selected states

With #647 we are adding the abillity to react on symbol click events. An extended use-case of this is to introduce selected states and showing an InfoWindow as result of it.

Start by reading issue #647 and the related symbol click event work to understand the existing entry point. Clarify the intended selected-state behavior and how an InfoWindow should be shown, then define tests or examples that demonstrate both behaviors before implementation.

Written by the indexing model from the issue text.