id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
10356	"""learn mode"" for ACF"	Alfonso Martínez de Lizarrondo		"Many people will disable ACF because it modifies whatever content exists upon initial load if the classes, attributes, styles... haven't been added to the allowedContent.

A simple example is the stylesheet parser: you have been forced to make it disable the ACF in order to have things work.

Instead, the ACF could have an optional ""learn mode"" that adds whatever exists in the initial source to the allowedContent for that instance (maybe even configurable to work only on elements/classes/attributes/styles)

So now the stylesheet parser doesn't need to completely disable ACF:
the first run of ACF sees some classes that aren't included in the ACF, so it adds those classes. Then the stylesheet is loaded and adds all the desired classes for the content. Nothing has been lost.
The user then tries to paste something from an external page and the ACF is run and cleans up removing anything undesired. If the user copies and pastes something inside the editor, then all that content now is allowed and no filtering happens. everyone is happy.
"	New Feature	confirmed	Normal		General	4.1