Learn the Studio Web UI
Custom dynamic preview page
In the DoubleClick Studio Web UI Preview tab, there's an option to preview your creative by inserting a test page URL for your ad. You can use this feature with the dynamic preview page to create custom ad slots to test your ads.
The custom page lets you position one or more ads at custom coordinates. It's especially useful for positioning an expanding creative on the right and left sides of a page to test expanding functionality. You can also use this page to add and position multiple ad slots to test tandem roadblock ads.