Like most graphics applications that deal with very large visual spaces, the Tecknaro zoom feature is sensitive to whether you are using the keyboard or the mouse to zoom.
If you use the keyboard to move around (via Ctrl arrow keys) and zoom in and out (via Ctrl + and Ctrl -), then you will always zoom in and out with the center of your window as the center of the zoom, which is more traditional desktop application behavior.
Alternatively, if you use the mouse to zoom in and out (via the mouse wheel), then the center of the zoom depends on the location of the mouse. This gives you a much greater degree of control of your visual space; allowing you to "push" the canvas away from you in one direction, look around from far above, and then "pull" the part of the canvas you want closer into view. This extra dimension of control may not feel right to you.
It's a personal preference thing, so we provide both interfaces.
If you like the "video game" mouse interface, use it.
If you prefer a more traditional interface, use the Ctrl arrow keys and Ctrl +/- to move around.