It's part of universal access, as W Lane as said. The keystroke combo to toggle this on and off is <control><option><command><8>. This has been in Mac OS for quite some time. On Nov 21, 2003, at 5:54 AM, Mark Taintor wrote: > I have a friend who's not on this list who's come down with a strange > problem with his G3 iMac. Here's what he told me: > > I brushed the keyboard nervously while speaking to my wife. I was > waiting for a web page to appear on AOL. All my colors reversed. I am > typing white letters on a black background right now! I went into > screen effects, desk top, colors, calibrate, millions of colors, etc. > Nothing worked. I reset about ten times. The colors are correct for > two seconds, then change to this kind of "negative" looking theme. > I formed another user, and the colors were fine, but all my files are > on MY identity. Very odd problem. > I have an Imac G3 with 305megs of Ram and 10 Gigs of HD. OSX right of > the box, first addition. No updates. > > Any ideas about what's wrong with his machine? He can access his files > now from a new user that he's created, but we're wondering if it's a > symptom of something more serious.