My iMac randomly began lowering the opacity of some of the windows that aren't on top one day and I can't figure out how to get it to revert to the original setting. It's a bit of an eyesore when there are a bunch of windows
http://farm1.static.flickr.com/221/470655371_ca967cb0af_b.jpg
Any ideas? I haven't manually tampered with any settings

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