Currently the block title (for content and text blocks) is used in the backend as well on the front-end. It should be possible to separate these titles.
New field: Published title
Checkbox: "Use title". When the checkbox is unchecked, it is replaced by a text field and a "Published title" can be entered:
When Title and Published title are exactly the same the checkbox should appear again.
It should be possible to use an empty "Published title". So an empty string in the database should be an an empty "Published title", while a null should use the "Title" (this also makes sure this feature is backwards compatible).