I seem to have a problem when adding html to a block (i'm using ckk editor), if i toggle Source it loses them html id tag. If I save the Block without toggling, it works fine, but when I go back in to edit the block afterwards, it has lost the div id tag. I have attached a pic which shows the problem in 3 steps. I have it set to Full HTML throughout.
I thinks, you must twig ckeditor config file, and set config.allowedContent = true. Please, see docs http://docs.ckeditor.com/#!/guide/dev_allowed_content_rules
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