This works:
<Window
x:Class="xxxxxx"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:telerik="using:Telerik.UI.Xaml.Controls"
mc:Ignorable="d">
<Grid>
<TabView>
<TabView.TabItems>
<TabViewItem Header="CMD Prompt"/>
<TabViewItem Header="PowerShell"/>
<TabViewItem Header="Windows Subsystem for Linux"/>
</TabView.TabItems>
</TabView>
</Grid>
</Window>
This does not due to the following. Using all of the latest nuget packages (2.0). I suspect it is related to being in a Window vs a control:
Microsoft.UI.Xaml.Markup.XamlParseExceptionHResult=0x802B000A
Message=XAML parsing failed.
Source=WinRT.Runtime
StackTrace:
at WinRT.ExceptionHelpers.<ThrowExceptionForHR>g__Throw|20_0(Int32 hr)
<Window
x:Class="xxxxxx"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:telerik="using:Telerik.UI.Xaml.Controls"
mc:Ignorable="d">
<Grid>
<telerik:RadTabControl>
<telerik:RadTabControl.Items>
<telerik:RadTabItem Header="Tab 1" Content="The content of tab item 1"/>
<telerik:RadTabItem Header="Tab 2" Content="The content of tab item 2"/>
<telerik:RadTabItem Header="Tab 3" Content="The content of tab item 3"/>
<telerik:RadTabItem Header="Tab 4" Content="The content of tab item 4"/>
</telerik:RadTabControl.Items>
</telerik:RadTabControl>
</Grid>
</Window>