I have what seems like a pretty straightforward task in QGIS: I have a shapefile that, in some cases, groups multiple separate landmasses into a single feature. For example, the Hawaiian islands are all one feature. How can I split those up into multiple features? This seems like it should be easy but it's proving impossible.
Using the "Split Feature" tool doesn't do anything when I try to draw a split line between the islands, or surround one of them. The "Singlepart to Multipart" option in the vector tools might do the job, but it's not selective, it just splits up EVERY multipart feature, when I only want to split up a few of them.
How can I pick a polygon that's one part of a multipart feature, like a single island in a chain, and split that out as a separate feature?