There was a discussion on moving from lightrooms develop to library and back again. Some complained about the time to go back and forth.
Short cut from develop to other library folders is here. In develop, look to the bottom where the thumbnails are. Right above the thumbnails, see the writing of details on the image. There is a downward v at the far right of the text. Click here and see all your library folders without ever leaving develop mode. Jon L
Develop to library and back