If a layer is built using a set of selected elements from another layer, the layer.featureset.name and featureset.filename remain null. Therefore it is not possible to save the layer. Meaning that featureset.save() raises an exception.
Comments: Please use issue tracker at [github](https://github.com/DotSpatial/DotSpatial) to post bugs.
Comments: Please use issue tracker at [github](https://github.com/DotSpatial/DotSpatial) to post bugs.