In order to access our internal Zabbix server from Internet, we use a reverse proxy.
Some operations fail when done through the reverse proxy.

For example, it appears that HTML code associated to fullscreen button looks like :
<div class="fullscreen menu_icon" title="Fullscreen" onclick="javascript: document.location = 'http://192.168.0.105:80/zabbix/screens.php?

Host name used in URL (here an IP address) is only valid within internal network but fails from Internet.

Attached patch solves this problem but I don't know if it would break something else.