' 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

' 导入命名空间
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Windows.Forms
Imports System.Math

public class MessageFilter
   public Shared Sub Main
         Application.Run(New Form1)
   End Sub
End class
Public Class Form1
    Public Class NoLeftDownMessageFilter
        Implements IMessageFilter

        Public Function PreFilterMessage(ByRef m As System.Windows.Forms.Message) As Boolean Implements IMessageFilter.PreFilterMessage
            Const WM_LBUTTONDOWN As Long = &H201
            Return (m.Msg = WM_LBUTTONDOWN)
        End Function
    End Class

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim no_left_down_message_filter As New NoLeftDownMessageFilter
        Application.AddMessageFilter(no_left_down_message_filter)
    End Sub

    Private Sub Form1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Click
        Application.UseWaitCursor = Not Application.UseWaitCursor
    End Sub
End Class
<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Partial Public Class Form1
    Inherits System.Windows.Forms.Form

    'Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing AndAlso components IsNot Nothing Then
            components.Dispose()
        End If
        MyBase.Dispose(disposing)
    End Sub

    Private components As System.ComponentModel.IContainer

    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.SuspendLayout()
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.ClientSize = New System.Drawing.Size(292, 273)
        Me.Text = "UseMessageFilter"
        Me.ResumeLayout(False)

    End Sub

End Class