At first it seemed useless to be the nth person to say how great this program is, but I can honestly say that if I had to choose one system extension to have, it would be this one. If you use your laptop all day like I do, this app will you hours a month. Without this app, add up all the time spent moving the pointer from your document, web page, email list, picture, spreadheet, etc. to the scorll button and back to where it originally was. Multiply by countless itmes a day. Hours of extra time to spend with my kids is well worth $15. Not to mention that each of the last 4 versions have worked flawlessly and very smoothly.