Arched top window treatments can be made to restrict certain portions of the window. You may not be requiring the treatment to be done on the Windows. : Likewise, most of the time there is the bottom and top approach used. In this approach the top and the bottom of the window is covered, The upper portion of the arc I covered with the fixed curtain and the same is applied to the bottom portion of the window. The middle part of the window can be used to get the sunlight. This concept is most commonly used in arched top window treatments.