When clicking on some buttons in the WordPress visual editor (ex: the button to create a link), browser does not respond correctly. The new window never becomes clickable/comes to the front of the screen. It is necessary to reload the page to continue. Same behavior does not happen in current release of Safari.
I can confirm this with the WordPress 2.8 demo site: http://wp.chrisjohnston.org/ The problem is in the Tiny MCE JS, so it might be reproducible with only Tiny MCE. This is the version information: var tinymce={majorVersion:'3',minorVersion:'2.1.1',releaseDate:'2008-11-27...
This was fixed in r41028: http://trac.webkit.org/changeset/41028 I was using Safari 4 to test. ;-)