protected override void WndProc(ref Message m)

Protected Overrides Sub WndProc(ByRef m As Message)

All messages are sent to the WndProc method after getting filtered through the PreProcessMessage method.

The WndProc method corresponds exactly to the Windows WindowProc function. For more information about processing Windows messages, see the WindowProc function documentation in the Windows Platform SDK reference located in the MSDN library at http://msdn.microsoft.com/library.

Notes to Inheritors:

Inheriting controls should call the base class's WndProc method to process any messages that they do not handle.