This policy setting allows you to manage the opening of windows and frames and access of applications across different domains. ...

This policy setting allows you to manage the opening of windows and frames and access of applications across different domains.
      
If you enable this policy setting, users can open additional windows and frames from other domains and access applications from other domains. If you select Prompt in the drop-down box, users are queried whether to allow additional windows and frames to access applications from other domains.

If you disable this policy setting, users cannot open other windows and frames from other domains or access applications from different domains.
      
If you do not configure this policy setting, users cannot open other windows and frames from different domains or access applications from different domains.