The biggest difference is in how you zoom. You use the left mouse to drag out four points, which serve as thecorners of the zoom box. Once you have a rectangle, you can then drag around any of the points.
On the zoom box, you should see an arrow pointingfrom Point One to Point Two. Point One will be mappedto the bottom left corner of the image, and Point Two to the upper left.
Point Three goes to the upper right, andPoint Four to the lower right.
You can select any quadrangle, even one with crossed sides. Once you are happy with the zoombox, all you have to do is right click to zoom in.