You can also generate graphics using HTML. Note: this works for graphics windows created using the Manager's Show Graphics button; it doesn't provide a screensaver.
In this case your main program supplies a URL that supplies the HTML. This may be an external URL, or it may refer to a web server embedded in your main program (i.e. a URL of the form http://localhost:port). Your main program can call
to register a URL to be used for graphics; in this case, the BOINC Manager's Show Graphics button will open a Web browser window to this URL.