This goes in Xaml
<Window x:Class="TestApp.MainWindow"
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:logger="clr-namespace:LoggerControl.Views;assembly=LoggerControl"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:TestApp"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Grid>
<logger:LogControl x:Name="LogView" />
</Grid>
</Window>
Set the Datacontext in code behind
var logger = new Logger.Core.Logger();
LogView.DataContext = new Logger.Core.LogControlViewModel(logger);
logger.Log("Test App working");