This policy setting allows you to define the user experience related to how pop-up windows appear in tabbed browsing in Internet Explorer.If you enable this policy setting the user cannot configure pop-up windows in tabbed browsing. You must specify one of the following values: 0: Let Internet Explorer decide. 1: Force pop-up windows to open in new windows. 2: Force pop-up windows to open on new tabs.If you disable or do not configure this policy setting Internet Explorer uses the user's setting for pop-up windows in tabbed browsing.
Windows Components\Internet Explorer
At least Internet Explorer 7.0