In JRA-4897 Owen describes how to add an icon to a portlet. If I understand him correctly, basically you have to put some gifs somewhere in the filesystem, i.e. outside your jar file.

However, I thought the whole point about the plugin system was that plugins were self contained in a jar file, so I can install them by simply by copying the jar to WEB-INF/lib. It shouldn't be necessary to add additionall gif files to make the plugin work.

Please provide a way to place the icons inside the jar file, for example by declaring
<thumbnail location="classpath">/my/company/portlet/preview.gif</thumbnail>, to load the icon from the classpath instead of the webapp root dir.