This is the legally remixed applet.
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=1036msg3842;topicseen#msg3842


I notice when the applet is downloaded and used as a standalone in the full screen view
the mask that covers the top answer is control by

maskrx=(x1+size+(n3-n2+step+2)*w*0.8); // by trial and error the position of mask

the text i2+"" is control by Pos X = x1+size+w*xshift

Is there a way to cleverly detect the width of the applet, and then calculated the amount to shift for each step of the answer?

currently the mask work well in current size of "750,600"

In full screen the mask move too much, but in current size of "750,600" the mask is nice and work well.