How can I set an attached property in code?

The following example shows how you can set an attached property in code.

[C#]

DockPanel myDockPanel = new DockPanel(); 
CheckBox myCheckBox = new CheckBox(); 
myCheckBox.Content = 'Hello'; 
myDockPanel.Children.Add(myCheckBox); 
DockPanel.SetDock(myCheckBox, Dock.Top);