' Follow steps 1a or 1b and then 2 to use this custom control in a XAML file. ' ' Step 1a) Using this custom control in a XAML file that exists in the current project. ' Add this XmlNamespace attribute to the root element of the markup file where it is ' to be used: ' ' xmlns:MyNamespace="clr-namespace:Effector.Plugin.Lib" ' ' ' Step 1b) Using this custom control in a XAML file that exists in a different project. ' Add this XmlNamespace attribute to the root element of the markup file where it is ' to be used: ' ' xmlns:MyNamespace="clr-namespace:Effector.Plugin.Lib;assembly=Effector.Plugin.Lib" ' ' You will also need to add a project reference from the project where the XAML file lives ' to this project and Rebuild to avoid compilation errors: ' ' Right click on the target project in the Solution Explorer and ' "Add Reference"->"Projects"->[Browse to and select this project] ' ' ' Step 2) ' Go ahead and use your control in the XAML file. Note that Intellisense in the ' XML editor does not currently work on custom controls and its child elements. ' ' ' Imports System.Windows.Controls.Primitives Imports EgwWPFBaseLib Public Class EffectorWindow Inherits EgwWPFBaseLib.EgtWindow Shared Sub New() 'This OverrideMetadata call tells the system that this element wants to provide a style that is different than its base class. 'This style is defined in themes\generic.xaml DefaultStyleKeyProperty.OverrideMetadata(GetType(EffectorWindow), new FrameworkPropertyMetadata(GetType(EffectorWindow))) End Sub End Class