Raising an event invokes the event handler through a delegate. For more information, see Raising an Event.
The OnMouseMove method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.
Do not call OnMouseMove if the button is disabled (this includes calls to the base class's OnMouseMove method when you override OnMouseMove in a derived class). When disabling the button in an override of OnMouseMove, call the base class's OnMouseMove method before disabling the button, or do not call it at all.
Notes to Inheritors
When overriding OnMouseMove in a derived class, be sure to call the base class's OnMouseMove method so that registered delegates receive the event.
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2