This came up while doing some Safari experimentation; it doesn't currently affect Safari. Calling -[NSWindow selectKeyViewPrecedingView:] was causing the WebFrameView to become the first responder. I tracked it down to a bug in -[WebFrameView becomeFirstResponder] that is easy to fix.
Created attachment 25107 [details] patch
Comment on attachment 25107 [details] patch > + // If we couldn't find a previous valid key view, ask the WebView. This handles frameset > + // cases like. Note that previousValidKeyView should never be self but can be due to > + // AppKit oddness. The second sentence of this comment has lost the Radar number. r=me
http://trac.webkit.org/changeset/38402