I am in the process of developing a custom user control derived from Control. It has textbox and a button. I managed to catch the button click. To dothis I have implemented dependecy properties and routed commands. Eg: in my generic.xaml <RepeatButton Command="{x:Static local:myInputBox.KeyPressCommand}">Up</RepeatButton> This is work fine. But I cant catch the textbox LostKeyboardFocus evnt. When I try to implement this like the way I did for the button, then getting an error as bellow. "not a valid event handler method name. Only instance methods on the generated or code-behind class are valid." Please help me to over come this problem. Apreciate your early response. Thanks.