In L3 I used to save an updated workspace by choosing its name from the list (usually it was the default, so I didn't have to choose anything, just answer yes when asked if I want to overwrite).
In L4 all I can figure out is to save the current snapshot by typing in the name again (and hoping I don't make a typo so that I end up with two similar named layouts and have to figure out which one to delete). Is there a better way to save a layout that has changed since the last time I worked in it?