Man, oh man, I really did not want to have to write this review, but I feel like I've been cheated.
TidyTabs is a great idea ruined by too many bugs. The developer is more than happy to answer questions before you buy it but, once he has your money, becomes non-responsive. The program hasn't been updated in almost a year, is riddled with bugs, and does a poor job of dealing with multiple displays and resolutions. Windows fly around, resize on their own, get grouped under other tabs, interferes with application dialogs (it absolutely destroys MS Word), and windows are randomly minimized or moved to other displays.
There is no option for support, the "report a bug" feature merely opens up their FAQ. The only way to report is to send him an email, which is fine but, again, he ignores them.
All of this would be tolerable if the dev was at least half-way responsive and tried to provide bug fixes. Three stars for the app but it gets knocked down to 1 star for the non-responsiveness after purchase. As of now, go with Groupy instead. That has bugs, too, but at least Stardock tries to fix them.