This is reproducible when you disable the automation peers by setting the AutomationManager.AutomationMode static property to Disabled.
It happens when you open a new RadWindow dialog (using the ShowDialog method), and the close it. After this, when you interact with the main window (click a button, hover a GridView, etc.) the exception occurs.
The exception is thrown only in the Output pane of Visual Studio and it doesn't cause any harm to the application. You can safely ignore it.
The exception message is "Invalid window handle".
To work this around you can enable the "Enable Just My Code" option in Visual Studio.
Moving a window fast on low performance machine or between two monitors causes incorrect offset to be applied to the mouse cursor
This happens when RadWindowInteropHelper.AllowTransparency is set to False and RadWindow is implemented as UserControl. The Window need to be maximized firstly on the main screen and then on the secondary in order for issue to be reproduced. The issue also affects the ToolWindow that RadDocking uses for its floating Pane. In order to reproduce the problem, the primary monitor needs to have its DPI higher than the secondary one.
<telerik:RadNavigationViewItem Content="Test" Foreground="Blue"/>
<TextBlock Text="Test" Foreground="Blue"/>
The ribbon tab doesn't get selec if you click in the exact middle of the header of RadRibbonTab.
To work this around, extract the ControlTemplate of RadRibbonTab and move the Grid with x:Name="ContentPanel" before the Grid with x:Name="HeaderPanel".
As of R1 2018 RadGridView supports pinning columns both on its left and right side. The new properties that control the right-side behavior are: RightFrozenColumnCount and RightFrozenColumnsSplitterVisibility.
Here is the link to the example in the XAML SDK Repository: https://github.com/telerik/xaml-sdk/tree/master/ScheduleView/Database