I would like to be able to move the current image in Loupe or Develop view to another folder, without having to return to Grid view. Ideally, this would be as simple as dragging the Navigator thumbnail to a folder or collection.
In case you didn't know: While you can't move a photo to an arbitrary folder or collection, you can set the current target collection. Right-click a collection in the Collections panel and do Set As Target Collection. Now, when you type "B", the current photo gets added to that collection.