Notes and image: http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.66/Usability - now each editor has own settings for "show panel header" and "show panel background", and colors+alpha for this. - this setting used to be global for all editors, but it can conflict with looks of specific editors. - Now you can set for editors to show panels with a 100% transparent tool/properties region. Note: read XML theme files now might get an error, Campbell will fix.