Typically we leave this check disabled and do not warn users that they are using a pop up blocker.
[[File:popup-blocker.jpg|thumb|none|500px|Object Viewtext]]
If you choose you can enable this check and warning message by doing the following.
# Go to the Template tab.
# Inside the '''Login Page Template''' text area search for '''disabled="disabled"'''
[[File:PBWarning1.png.png|thumb|none|500px|text]]
# Remove the '''disabled="disabled"''' text.
# Press save.