The GUI is implemented as follows: on the graphic loaded in the
graphics viewer, users can click the right mouse key to activate
the tool page. A total of 8 tool balls are aligned in a circle around the
center (101), and each tool icon has a circular active area with
radius of 16 pixels (102). These tool balls are evenly distributed in
a circle with radius of 70 pixels (103) (Fig. 6, left). When the mouse pointer is moved onto any tool ball, users can use the left mouse
key, scroll up, and scroll down of the wheel to execute specific
software functions (Fig. 6, left). This new wheel-based GUI is called
“the wheel tool area”