WordPress 3.9 was released on 16th April 2014. We spent most of the 17th April re-testing the compatibility of our plugins with the final version. The readme.txt files in the plugin repository on WordPress.org have been updated to reflect this.
The oik base plugin was the only plugin that needed to be updated. oik version 2.2 now supports TinyMCE Version 4.0 in WordPress 3.9 and TinyMCE version 3 in previous versions of WordPress.
For continued support of the oik options Buttons dialogs we recommend you upgrade to oik version 2.2 when you upgrade to WordPress 3.9.
For other changes see oik v2.2