#610234 by Gábor Hojtsy, ksenzee, cwgordon7, David_Rothstein, seutje, marcvangend, sun, JoshuaRogers, markus_petrux, Bojhan, Rob Loach, Everett Zufelt, drifter, markboulton, leisareichelt, et al: Added Overlay module to core, which shows administrative pages in a JS overlay, retaining context on the front-end site.