Dynamic legends for unfilled polygons

[IlkaIllers1]

Very often, I have to display administrative data like municipalities, counties or state. This leads to a problem since the legend for a map series is often supposed to be dynamic and only show features visible in the map extent.

Since all these areas are displayed as unfilled polygons, if the boundary doesn't happen to be in the map extent it looks as if they aren't visible - but they appear in the legend because they are, they are just not filled. The only way around this is to change the polygons to polylines.

I would love an option similar to "Only show features visible in the map extent" that says "Only show features where the polygon boundary is visible in the map extent" (obviously only enabled for polygons).