Hello yjh,

You can set IsRestricted property of the RadWindow to true. This will restrict moving the window only in the browser area. You can further set RestrictedMargin if you want to restrict the RadWindow in a smaller area. Hope this helps.

Greetings,
Boyan
the Telerik team

Sorry, I didn't notice IsRestricted property, it is good  now.

But I find that when maximize RadWindow, the left and right border out of the browser even set IsRestricted to true.
if set RestrictedMargin to new Thickness(5,0,5,0), RadWindow seems to be cut off left and right side.

Hi yjh,

This behavior is by design. When you maximize the RadWindow the right and left borders disappear. It is exactly the same as in Windows explorer. Only Windows 7 them keeps the borders by default. If you want to keep the borders you have to edit the template of the RadWindow.

All the best,
Boyan
the Telerik team