Unity: how to make windows resist overlapping each other?

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http://askubuntu.com – I just upgraded from lucid/gnome2 to precise/unity. In gnome2, if you try to drag one window next to another one, there is a pause* when their edges meet so that you can align them perfectly. What is that behavior called? Can I get it in unity? * The window stops moving once its border touches the border of another window, even as the mouse continues to move. After the mouse has moved maybe 5-10 more pixels, the window resumes moving along with the mouse. (HowTos)