I'm running OS X 10.6.4. In various browsers (Firefox and Safari), pressing Shift-Tab closes all tabs and windows of the browser. This is contradictory to Apple's keyboard shortcuts page, which describes Shift-Tab as navigate through controls in a reverse direction. I checked System Preferences - Keyboard - Keyboard Shortcuts and don't see any Shift-Tab mappings.
Is there a way to disable or change this? It's quite annoying to accidentally press Shift-Tab and have the entire browser shutdown.
Follow up: It seems Shift-tab will close any application that I'm in. System Preferences - Keyboard - Keyboard Shortcuts "Restore Defaults" doesn't seem to help.
Follow up 2: It seems that this may be related to Safari 5. I'd be interesting if anyone else is seeing this after upgrading to Safari 5.