Remora Pattern by Ben Constable

According to Ben Constable, Remora Pattern allows you to attach a chunk of logic to any existing element that you have. This pattern can be implemented using an Attached Dependency Property in WPF. Here an Attached Dependency Property is attached with an object. When the object is initiated, it goes to set the value of the Attached Dependency Property, which results in calling an Attached Dependency Property Change event. In the event handler, you can add your intended functionality, which is the additional functionality of the object.

You can get more info about this pattern  in Ben Constable's blog. You can take a look at it here. I have written an article using Remora Pattern to implement a Touch Screen Keyboard. You can take a look at it here (no advertisement intended).