The early release of version 2.6.5, which was one of the rare bugfix releases, made it perfectly clear that even changes that only affect one single line may have serious consequences.
TYPOlight version 2.6.4 is available. The maintenance release includes a few improvements of the permission system (regular users can now create news archives, calendars, forms etc.), a new TinyMCE plugin to insert lightbox images and some important bug fixes, thereunder a TinyMCE update to version 3.2.1.1 that hopefully fixes the issue with the rich text editor not showing up occasionally.