Illustration of the problem
When a web page in Firefox switches to full-screen then even though the website is allowed to switch to full-screen automatically (Tools > Page Info > Permissions > Enter Fullscreen) Firefox show this annoying message for whole three seconds:
I know that I can disable the messages using this option
false. Unfortunately this option disables the message also for unapproved websites and the approval confirmation "Remember this decision for ..." does not ever show up:
I do not want to undergo the security risk and disable the messages completely but the message from the first screenshot is too obtrusive for me. Is there any solution? For me ideal would be to show the message for a considerably shorter time like half a second. I also can accept not showing it at all but only for allowed websites.