Distinguish editable and uneditable text within unmovable blocks [#67622822]

Before:

![image](https://f.cloud.github.com/assets/206973/2528060/b714175e-b50b-11e3-907f-e61d0b787b57.png)

After:

![image](https://cloud.githubusercontent.com/assets/206973/2530741/1905df56-b52a-11e3-8286-4b225bb0df09.png)