change the blank page until openmeetings switches on rtmpt protocol

[SCOYER Fabrice (Chef d'unité) - CETE Lyon/SG/INF]

Hello,

I use OpenMeetings via a reverse proxy to provide access from a chain of 
proxy.

By default, so I use the protocol rtmpt, and when I connect to the 
website I have to wait 3 unsuccessful attempts before OpenMeetings 
switches on protocol rtmpt.

During this waiting (a bit long), users have a blank page. Is there a 
way to insert such a simple animated gif (like please wait ...) in this 
blank page.

Thank you for all your suggestions.
cordially

Fabrice