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Gordon R. Meyer
ScreenFloat - A tool for Mac OS X writers
Writing software documentation largely consists of looking at the product you're writing about, while you're writing. This is easier if your computer has multiple monitors, or if you have two computers, so you aren't constantly switching between your writing and the subject. If you're working from a notebook computer, or documenting a full-screen application, then you have my sympathy.
Mac users, however, can turn to a nifty little tool called ScreenFloat. It lets you easily capture a a portion of a screen and display it in a floating window so it's "above" your writing tool. This means it never gets obscured and you can refer to it easily while you're writing. It also keeps a library of previous screenshots which might be handy for resolving those "I swear it used to work differently before" moments.