Clean disallowed attributes in a post-fixer

[pjasiun]

We should try to replace Schema.removeDisallowedAttributes method, which needs to be manually called, with a postfixer which will automatically remove disallowed attributes.

[Reinmar]

Right now this method is only used in deleteContent and insertContent. So all other algorithms (e.g. paragraph/heading/list commands) leave incorrect attributes in the model.

[Reinmar]

I changed the title of this ticket because it's not about replacing the existing method, but about adding a post-fixer.

[Reinmar]

ckeditor/ckeditor5-list#104 will add a code which will need to be removed once this ticket is solved.

[Reinmar]

DUP in https://github.com/ckeditor/ckeditor5-engine/issues/1691

[Reinmar]

It seems that with more attributes for blocks in the model, the importance of this issue rises.

In the example below I was able to indent list items with margins, which is not allowed normally. I did that by turning indented paragraphs to a list.

[kuku711]

@Reinmar This issue gonna be resolved?
You mentioned this is critical, why it doesn`t get prioritize?
This issue should be as a bug and not improvement....

[CKEditorBot]

There has been no activity on this issue for the past year. We've marked it as stale and will close it in 30 days. We understand it may be relevant, so if you're interested in the solution, leave a comment or reaction under this issue.

[CKEditorBot]

There has been no activity on this issue for the past year. We've marked it as stale and will close it in 30 days. We understand it may still be relevant, so if you're interested in the solution, leave a comment or reaction under this issue.

[CKEditorBot]

We've closed your issue due to inactivity over the last year. We understand that the issue may still be relevant. If so, feel free to open a new one (and link this issue to it).