Making cookie name 'zbx_sessionid' configurable

I have several Zabbix servers running, and would like to see all the frontends in browser(s) on one PC.
In Windows, cookies are shared between browsers/tabs, therefore a Zabbix session will be broken by later login to another frontend.
It would be nice that the cookie name 'zbx_sessionid' is configurable in zabbix.conf.php with $ZBX_SESSIONID, for example.