I could not find a four-button mouse when shopping at a couple of stores for a new mouse. There were a few wired usb connected mouses and many wireless mouses. Nearly all of these had either two buttons and a middle wheel, or three buttons and a middle wheel. NONE of them had four buttons. I really wanted to find one of those four button mouses, with the left SIDE button to make a browser go BACK and the right SIDE button to make the browser go FORWARD. Are these kind of mouses now obsolete? What do we call these kinds of mouses?