Here Gemini is using images for its Entries instead of text. It does this by setting the UseImages parameter to 'yes' so that Gemini interprets the values in the Entry parameters as image locations.

The images you use for entries mustn't be any wider than the HeaderImages, and these are the same width.

You can also see Testmode in action here: move the mouse over the applet and you'll see the suggested width and height for the applet in the browser's status bar. (As always, you should use Testmode in Netscape Navigator since this is the browser that claims the most real estate for an applet.)