Windows Forms Interoperability

UserControl on a Windows Form (Design Time)

Add a reference to "Windows.Base"
Add a reference to "System.Xml"
Add a reference to "Presentation.Core"
Right click on your project and select (Add > New Item)
Choose "UserControl (WPF)" and provide a name of "UserControl2"

Build your project.

Drag an ElementHost control from the Toolbox onto your Windows Form
Change the Dock property to Fill
Resize the windows from to match the size of the WPF user control
Right click and choose, Select Hosted Content
Click on the very small arrow in the top right corner
In the Selected Hosted Content, select your usercontrol

UserControl on a WIndows Form (Run Time)

System.Windows.Forms.Integration.ElementHost ehost = new System.Windows.Forms.Integration.ElementHost(); 
ehost.Size = new Size(10,10) 
MyUserControl ocontrol = new MyUserControl(); 
ehost.Child = ocontrol; 
this.Controls.Add(ehost); 

Windows Control on a WPF panel

Add a reference to:
WindowsFormIntegration
System.Windows.Forms

Create a grid element to insert your windows forms panel into
In the Design view display the Properties window
Click the Events tab and double click on the Loaded event
Add the following code to the Loaded event