Allow the user to move only if he presses SHIFT

At the moment there is a big issue in browsing photos. The point of view changes too easily.
Even if you shoot perfectly, like I did in this synth http://photosynth.net/view.aspx?cid=f... you can see that you jump from one point to the other.
I don't want that. I want to rotate around one point if there are available photos, and only allow the program to jump to another point when I want.