Popup's draggable Area of Movement Limited

Question

In my application I am invoking a PopUp by

Popup pop = new Popup;

then i add this:: pop.child(page); where "page" is the instance of a XAML page which is of type ChildWindow. Now when the popup shows up on my MainPage, it becomes Non-Modal just like I want it to be!! But the problem is, the popup window is not draggable through out the Mainpage. I know that the popup appears within the Boundaries of a Silverlight control hosted in a browser. And It's not a true window. But still my popup is not draggable within its boundaries.. Am i missing some declarations which define the draggable region of a popup control OR is it the ChildWindow which needs to be configured ??