I hate to admit it, but it's been a really long time since even I've used Lyrics Editor. But... I think there's an option in it somewhere to filter out files that have lyrics. If not, you can just use the smartlist trick that Magic_Randy mentioned. It may perform better that way anyway.
And as for the whole internal browser thing... I wanted there to be a way that you could just highlight the lyrics you wanted and click a single button and have them automatically added to the file. It would just be easier than right clicking on the lyrics, choosing copy, closing the browser window, and then pasting them in. The down side to that is that it requires using .NET's IE engine, which, as Magic_Randy pointed out, did nothing to stop popups. So that's when I added in the option to use the default browser instead.
I keep thinking of getting back to this plugin and doing a couple of updates on it, but I always wind up finding other things to do to occupy my time with. It's good to hear people are still finding it useful, though.