I have a bizarre phenomenon with Firefox.
In some pages fckeditor shows off well but sometimes the seizure-page of the text contained in the tag iframe is not displayed.
Although the toolbar is present.
Sometimes it shows off again at the time what I refresh (F5) the navigator's page.
It makes me the same problem on the Demo-page of http://www.fckeditor.net/demo/default.html
Bad working with Firefox 188.8.131.52