RADWINDOW and Maximising with button

[Hicham]

Hi,
I have an issue with the RADWINDOW when i want to maximise it with the button Maximize, the window doesn't take the full screen mode and the borders disappears(image in attachement) but when i double click on the task bar, it works correctly

below the code i use :

public static void NavigateToModal<T>(OpraViewName name, ParameterizedMessage message = null) where T : UIElement, new()
        {
            _message = message;

            object view = null;
            int Width =0, Height =0 ;


            switch (name)
            {
                case OpraViewName.AboutView:
                    view = new AboutView();
                    Width = 1000;
                    Height = 600;
                    break;
                case OpraViewName.ArticlePickerView:
                    view = new ArticlePickerView();
                    Width = 1000;
                    Height = 600;
                    break;
                case OpraViewName.ArticleLoaderView:
                    view = new ArticleLoaderView();
                    Width =  700;
                    Height = 600;
                    break;
                default:
                    break;
            }



            RadWindow modalWindows = new RadWindow();
            modalWindows.WindowStartupLocation = WindowStartupLocation.CenterOwner;
            modalWindows.MinHeight = Height;
            modalWindows.MinWidth = Width;
            modalWindows.Header = name.GetStringValue();
            modalWindows.Content = view;//The view is the user control i use
            modalWindows.ShowDialog();

        }

thanks.