Hi,
If I create a new Custom HTML Module, the editor field is locked and I can not insert code or text.
I tried to open an existing form, same problem.
To unlock the field I have to select "Fullscreen" at this point the editor is released, and the text appears.
The bug occurs with Safari 6, Firefox 20 and Chrome 26, running Mac OS X 10.8.3
Joomla 3.0.3 - Gantry 4.1.9 and MAMP
I enclose a short video where you can see this annoying bug: