In my opinion that's a lot better than the old version, thanks!
Maybe you could think about the option of switching to the move cursor as long as the user keeps the mouse button pressed after clicking in the navigator (same thing that happens when one clicks into the red box directly).
This would allow to move to a different section of the diagram and to fine adjust the view with just one click.
Btw, can you reproduce the inaccuracy while zooming by mouse wheel?