This shows how the computed style of each node differs from the computed style of its parent. The root element, which has no parent, is instead compared against the root of a blank HTML document.

* create a new bookmark called "compute styles" in your firefox toolbar. Place the snippet code in the location field of your "compute styles". click the compute styles bookmark, then click an element on the page with the crosshairs.

List all plugins installed in FF

Just a little code to make a window in XUL