Mosaic, from Light Pillar Software, is the successor to Window Tidy, which is being retired. If you’re familiar with Window Tidy’s workflow, you’ll be comfortable with Mosaic from the start; if you aren’t familiar with Window Tidy, you’ll still find Mosaic very easy to use: drag a window, an overlay appears with layouts from which to choose, drag your cursor to the layout you want to use, and your window snaps to the size and location defined by the layout.
I found all of the features to be extremely fast and very convenient. Mosaic offers a great deal of control, including three options to determine how the overlay is triggered. There are some pre-determined, standard locations, called Quick Positions, which don’t alter your window size—which you’ll really like if you have your window just as you want it, but need to move it quickly. The layout selections are powerful, letting you divide your screen into sections when you need to reference data from different apps. And Mosaic places some really nice space between windows to provide visual differentiation—gutters—making them not only more visually pleasing, but also more rationally functional in a work environment. One of the features I found most useful was Quick Layouts, which lets you “paint” your window size and position on a grid. I know this feature can be found in similar software, but Mosaic lets you divide the screen into very small tiles, and allows you to eliminate the outer gutter (along the edge of the screen) completely, which means you can, well, paint yourself into a corner, which I do. Sometimes. :-#
A lot of these features—and more—are available only in the Pro edition of Mosaic. Skip the Standard edition unless your needs are few; I suspect most of you are power-users who need serious window management, and the Pro edition of Mosaic is feature-rich, providing everything you could want, including a very pleasant experience.