As a counterpoint to most comments here, I've been using Polypane for a couple years now and it's been an invaluable tool in my arsenal. I don't mind that it's

As a counterpoint to most comments here, I've been using Polypane for a couple years now and it's been an invaluable tool in my arsenal. I don't mind that it's not open source, it's made by an indie dev that's super responsive and really cares about helping people making better websites. Keep it up, Kilian!