When a RadSplitContainer with Orientation="Vertical" contains RadPaneGroup instances, resizing them causes a flicker when the ShowResizePreview property is set to False. This happens with the VisualStudio2019 theme.
For the time being, a possible workaround is to create a global Style with TargetType="RadPaneGroup" and set the Margin property to "0":
<Style TargetType="telerik:RadPaneGroup" BasedOn="{StaticResource RadPaneGroupStyle}">
<Setter Property="Margin" Value="0"/>
</Style>
The DataContext of RadPane's content is lost when showing its preview in the DockingNavigator.
As a workaround, you could set the DataContext of the content element could be set explicitly.
The RadOutlookBar control takes a significant amount of time to load initially when it does not have a fixed width and its IsMinimized property is explicitly set to True.
A possible workaround, for the time being, is to set a fixed Width for the control and change its value in the Minimized and Restored events.
public
MainWindow()
{
AutomationManager.AutomationMode = AutomationMode.Disabled;
InitializeComponent();
}