' Creates a message filter.
<SecurityPermission(SecurityAction.LinkDemand, Flags := SecurityPermissionFlag.UnmanagedCode)> _
Public Class TestMessageFilter
    Implements IMessageFilter

    <SecurityPermission(SecurityAction.Demand)> _
    Public Function PreFilterMessage(ByRef m As System.Windows.Forms.Message) _
    As Boolean Implements IMessageFilter.PreFilterMessage
        ' Blocks all the messages relating to the left mouse button.
        If ((m.Msg >= 513) And (m.Msg <= 515)) Then
            Console.WriteLine("Processing the messages : " & m.Msg)
            Return True
        End If
        Return False
    End Function
End Class

// Creates a  message filter.
[SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
public class TestMessageFilter : IMessageFilter
{
    public bool PreFilterMessage(ref Message m)
    {
        // Blocks all the messages relating to the left mouse button.
        if (m.Msg >= 513 && m.Msg <= 515)
        {
            Console.WriteLine("Processing the messages : " + m.Msg);
            return true;
        }
        return false;
    }
}

   // Creates a  message filter.
   ref class TestMessageFilter: public IMessageFilter
   {
   public:
      [SecurityPermission(SecurityAction::LinkDemand, Flags = SecurityPermissionFlag::UnmanagedCode)]
      virtual bool PreFilterMessage( Message % m )
      {

         // Blocks all the messages relating to the left mouse button.
         if ( m.Msg >= 513 && m.Msg <= 515 )
         {
            Console::WriteLine( "Processing the messages : {0}", m.Msg );
            return true;
         }

         return false;
      }

   };