1. Set RadGridView's setting DragElementAction="ExtendedSelect". 2. Open a window on selecting a row. 3. Close the window, the RadGridView becomes ExtendedSelect. Note: Most probably this problem is actually caused by a limitation in the Silverlight platform. Once a Window is shown, there is no way to detect that the mouse is released.
The problem is actually caused by a limitation in the Silverlight platform. Once a Window is shown, there is no way to detect that the mouse is released and that's why this behavior occurs.