Feature summary: In Kartographer mapframes, a glow should be added to show selected features

Use case(s): In many cases, features such as lines aren't distinguished by their properties. For example, railroad system maps show coloring by usage, not by difference between individual lines (see the map at https://en.wikipedia.org/wiki/Pennsylvania_Railroad). So, when a feature is selected, the user has no way to distinguish what is encompassed by the feature selected. Adding a glow to the selected feature would solve this disambiguation

Benefits: This would add disambiguation to maps where properties shouldn't distinguish between features