Moving partitions between disk areas not well documented.
It turns out you can "Move" a partition between areas of a disk be using "Copy" and "Paste", "Delete"-ing the original, and only then "Apply"ing the operations. This isn't apparent, and not particularly documented. The key here is you must "Delete" before the "Apply" or you wind up losing all the special partition information (name, uuid, number) from the original.
It might benefit from having a "Cut" operation, to implicitly do the non-obvious required step.
It might benefit from having something about this on the "Resize/Move" dialog. (or even a button to initiate a move to another area.)