Here is more about using QuickJava from the developers:
Install the extension and restart your browser to get the Statusbar icons. Configure the options by right clicking on any visible icon and selecting “Options”. Select which icons to display which Statusbar icon’s you would like, customize the toolbar with which buttons you choose and enjoy. It’s that simple! There are way more options to play with, for help with those right click any visible icon and select “Help and FAQ”.
So there you have it. If you want to pick up QuickJava, you can do so at the Firefox Add-ons website.