We tried to use templates with some editable region.  It's sound great but we are not able to block the external region of the template.

In technical word, all the content is content in a tag <div id="template" contenteditable="false"> ... </div>.
And the part to edit are content in <div id="area1" contenteditable="true"> ... </div>.

But, in the editor, the user can add content out of the main div named "template".

 

How can we block this ?