Comment 35 for bug 582809

Serkan: that inability to click & drag is probably due to the mouseclick-event not registering a secondary click as an event, with the finger on the trackpad itself being the primary click (touch the touchpad -> click left mousebutton area -> drag). If the drag-event is from a secondary click and the mousebutton is the primary click (don't touch anything -> click left mousebutton area -> drag) it works though. Seeing how primary and secondary clicks already work somewhat, it should be possible to fix that behaviour without going to multitouch-APIs like MPX or Xi2....

also, a middle mouse button would rock! ;-)
Looking at your patch that should be fairly easy to implement, and since you cannot use left+right click to simulate it on that clickpad it would really be useful, seeing how many Linux-users use the middle klick, e.g. in the shell...