Currently there is no way to restrict a ToolWindow to not go outside of the screen. Although you can use the events of the ToolWindow to implement this yourself. I prepared an example that demonstrates the idea - an attached property set trough an implicit style to the ToolWindow control.

Please refer to the attached project.

private void ShowNewsView(NotificationMessage msg)

{
UserControl view = new UserControl ();
 view.DataContext = msg.Sender;
RadSplitContainer container = GetRadSplitContainer(view, "News", new Size(400, 300));
 radDocking1.Items.Add(container);

}

 private static RadSplitContainer GetRadSplitContainer(UserControl view, string header, Size size)
        {
            RadSplitContainer container = new RadSplitContainer() { HorizontalAlignment = HorizontalAlignment.Stretch, VerticalAlignment = VerticalAlignment.Stretch };
            RadDocking.SetDockState(container, DockState.FloatingOnly);
            RadDocking.SetFloatingSize(container, size);
            RadDocking.SetFloatingLocation(container, new Point(250, 50));
            RadPaneGroup radPaneGroup = new RadPaneGroup();
            RadPane radPane = new RadPane()
            {
                CanUserPin = false,
                CanDockInDocumentHost = true,
                Content = view,
                Header = header,
            };

            radPaneGroup.Items.Add(radPane);
            container.Items.Add(radPaneGroup);
            radPaneGroup.SetValue(RestrictToolWindow.IsRestrictedProperty, true);
            return container;
        }

Your Help will be appreciated! Thanks

 It doesn't matter how you create the panes - the implicit style should apply anyway. The problem must be in something else. Could you please open a support ticket and send us a sample project that reproduces the problem? This would help us investigate what the problem is.

There is no example for this feature yet. To enable the feature you need to set the IsRestricted property of the RadDocking control to true and to set the RestrictedAreaMargin to the desired value. RestrictedAreaMaring is of type Thickness and represents the the offset from the Silverlight plugin which restricts the RadWindow control. We are currently working on a help article about this feature.

Hope this helps.