You can use particleset or trace for your case.
"Particleset" only show points as small dots, however, trace will connect points with line.
You can play with it or look at the examples. You should be able to find examples for most of the GUI elements.
It is under Simulations/_examples/Elements/
If you have some background in programming, you should be able to pick up ejs in a short time.
I just went to University of Malaysia to for 3 days EJS workshop last week, to teach their faculty members how to create simulation with EJS. Please check out the examples in this forum. If you can understand Chinese language, there are more information about EJS at my [url=http://enjoy.phy.ntnu.edu.tw/course/view.php?id=246]online ejs course.[/url] You will find many step by step examples shown as flash movie.