I used protostar, and there was no option for sidebar drop down menus. I previously created Main menu (at the top of page) with so many menu-items. I downloaded this extension for J3, published, placed in position 7, and pointed to EXISTING menu. Like a charm! I got my drop down (on mouse hover) and used menu I was creating 5 hours, so spare time as well. Actually, I have tried this exact extension - from ARI, because for the same site, I already used Ari Image Slider 2.0.2, and it worked great, so I believed this one will also work good - and it does!