These changes, announced in a recent NLM Technical Bulletin, are now live:
"Limits" now appears as an option on the one line search screen - it did appear only on the Advanced Search screen for a while.
If you switch from one line to Advanced search, the one line search that you have been doing is now cleared - it used to stay there.
The Advanced Search screen will change - instead of the present three lines, with option to add more, there is a "search builder" - I had thought that this would enable you to add as many lines as you like, with the appropriate Boolean operators in between but in fact it seems to add your search terms to the basic search box, with the Boolean operators you choose. This seems a little like the "send to search box with..." that appears in the MeSH browser.
This post replaces the original, which had an inappropriate comment added that I could not work out how to remove.