Got it to work .. at least for what I need it for.
Change :
`<?php $_zp_authority->printLoginForm(NULL, true, $_zp_gallery->getUserLogonField(), false, gettext("A password is required for the page you requested")); ?>`
To :
`<?php $_zp_authority->printLoginForm($_SERVER['REQUEST_URI'], true, $_zp_gallery->getUserLogonField(), false, gettext("A password is required for the page you requested")); ?>`