Currently some desired Selection-related interactions require a slightly convoluted path through the code, because (for example) we want the standard UE editor gizmo to have "click precedence" over our selection click behaviors. However we will get the input event first, so we need to be able to check if the gizmo is hit via a callback function provided by the EdMode owning the ToolsContext this Interaction will be registered in. Similarly we need to be able to filter out hits if a closer visible object is hit, because there is no higher-level Behavior that will do that for us. (This may be improved in future, if more of the existing Editor interaction behaviors are re-implemented as InputBehaviors)