The OnMouseMove method is called before any event handler for the MouseMove event is called. This method allows derived classes to handle the MouseMove event without attaching a delegate. This is the preferred technique for handling the event in a derived class.
This implementation marks the MouseMove event as handled by setting the Handled property of the event data to true.
TextBox handles cursor placement and selection in MouseMove event. Derived classes can prevent the TextBox from processing the TextBox event by setting the Handled property of the event data to true.
Notes to Inheritors
When overriding OnMouseMove method in a derived class, be sure to call the base class’s OnMouseMove method so that registered delegates receive the event.