Hello,
I did not follow any link: I just used a locally installed gluu 3.1.2 distribution with oxauth-rp enabled (https://server/oxauth-rp/home.htm).
As mentioned in my first post,the problem does not occur in my 3.0.1 installation.
It seems to me that the embedded javascript at the end of the ```oxauth-rp/home.htm``` HTML page (just before the ```<div class="footer">``` element) does not behave the same. (It's just a guess: I am not a javascript programmer.)