Extending the properties of WPF controls(WPF Application)

Hi all,

        I want to add new properties to the WPF controls.

In VS2005:

[System.ComponentModel.Category("SCI Property"), System.ComponentModel.Description("Our own propery")]

public string MessageString

{get{return MsgString;}set{MsgString = value;}}

I tried this way in WPF application. But, didn't work....

Please guide me.........

thanks in advance....