Dependancy property

You go on this link   this is nice tutorial on It

The purpose of dependency properties is to provide a way to compute the value of a property basedon the value of other inputs.

These other inputs might include system properties such as themes and user preference, just-in-time property determination mechanisms such as data binding and animations/storyboards, multiple-use templates such as resources and styles, or values known through parent-child relationships with other elements in the element tree.

It has Following capabilities:

• The property can be set in a style.

• The property can be set through data binding.

• The property can be set with a dynamic resource reference.

• The property can inherit its value automatically from a parent element in the element tree.

• The property can be animated.

• The property can report when the previous value of the property has been changed and the property value can be coerced.

• The property reports information to WPF, such as whether changing a property value should require the layout system to recompose the visuals for an element.

• The property receives support in the WPF Designer for Visual Studio. For example, the property can be edited in the Properties window.