Fig. 9a shows the toolbar of a picture viewer in Windows XP. At
first, the participants were required to use the method “mouse
click þ toolbar” (Fig. 9a) to execute the following six functions: (1)
previous graphic, (2) next graphic, (3) zoom in, (4) zoom out, (5)
scroll clockwise by 90, and (6) scroll counterclockwise by 90.
Second, the participants executed the above functions using the
proposed “mouse wheel þ tool ball” (Fig. 9b). The detailed operations
of the tool balls are shown in Table 1. Then, the operation
times of the two user interfaces were calculated.