Lock Arc Rotate in User View

Hi All,

Is there any technique or way to "Lock Arc Rotate in User View".

Most of the time its very frustrating, because the arc rotation of prospective viewport is "Alt + MMB (Middle Mouse Button)", and most of the time we modelers rotate the prospective viewport in this way. And I am very use-to with Alt+MMB.

But the problem is, most of the time while in 2d viewport, accidentally my 2d viewport rotated to user view.

My opinion is, if there is a technique, which can lock the "Alt+MMB" while we are in the 2d viewport.

I know "Shift+Z" is undo of viewport, but I wish to lock the 2d viewport.

Subhendu