I just bought a new mouse for my mac. Previously, my old mouse had a middle click button in which I swore by. I used it in firefox to middle click links so that it opens up in new tabs and I also hovered over the tab and middle clicked to close it. My new mouse has no middle click but instead it has one programmable button in which case it's a small compromise. What can I set it to perform the same as my lovable middle click?