Changes

Using <code><panel></code> elements to float chrome UI over the main window leads to performance problems. In fact, any XUL element that creates a native OS window under the covers will slow things down. In Firefox, the awesomebar autocomplete list uses a <code><panel></code>. The autocomplete list was re-worked such that it was a <code><vbox></code> in the main <code><stack></code> and the results were dramatic. The list displays much faster.