I use my MMB in 2.48 to pan around. I have not been able to find the option in 2.55 to make the MMB pan vice rotate. I know it’s hidden somewhere, but I haven’t had any luck in finding it.
If someone could point me in the right direction, I’d appreciate it…
I believe what you looking for is accomplished with Shift-MMB.
[Edit]: Sorry, my bad. I didn’t realize exactly what you were referring to.
]It’s a little tricky. Go to User Preferences, and the Input tab. Type View3D into the search box at the top, and choose View3D from the choices that pop up beneath it (a little counter-intuitive, that). Next, click the Edit button, and hit the arrows next to View3D.move and View3D.rotate. Uncheck the Shift box for View3D.move, and check the Shift box for View3D.rotate, then save your settings.