屏蔽TextBox的系统菜单 
     TextBox是最常用的控件之一,很多时候我们需要处理在其上的右键处理.而系统默认有右键菜单, 因此很多时候影响程序的美观.其实,我们可以将系统的右键菜单屏蔽掉.屏蔽TextBox右键菜单的 方法有很多,下面主要介绍常用的两种方法:

方法一:投机取巧法;
本方法实现起来十分简单,在某些场合下使用起来很方便;不足是有些场合下不适用.
>>步骤1----建立新工程,在窗体上放置一个TextBox;
>>步骤2----在窗体上创建一菜单,设其Name = a;Visible = false;
>>步骤3----编写如下代码:
Private Sub Text1_MouseDown(Button As Integer, Shift _
    As Integer, X As Single, Y As Single)
    If Button = vbRightButton Then
        Text1.Enabled = False
        Text1.Enabled = True
        PopupMenu a
    End If
End Sub

>>步骤4----编译运行,在TextBox中按下鼠标右键,看看,系统菜单不见了,弹出的只是你自己定义的菜单. 简单吧!


方法二:截获系统消息法.
本方法实现起来相对来说,麻烦些,不过,应该说这种方法放之四海而皆适用.
首先取得系统函数的地址,并保存,然后用自定义的函数代替系统函数,最后恢复系统函数,弹出自定义菜单.
请看下面的代码:
>>步骤1----建立新工程,在窗体上放置一个TextBox; >>步骤2----在窗体上创建一菜单;设其Name = a;Visible = false;
>>步骤3----添加以模块,加入如下代码:

Public OldWinProc As Long' 保存系统窗口函数的地址
Public Const WM_CONTEXTMENU = &H7B' 当右击文本框时，
系统发送这条消息

Public Declare Function GetWindowLong Lib "user32" Alias _
    "GetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long) _
    As Long
Public Declare Function SetWindowLong Lib "user32" Alias _
    "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, _
    ByVal dwNewLong As Long) As Long
Private Declare Function CallWindowProc Lib "user32" Alias _
    "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hWnd _
    As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal _
    lParam As Long) As Long
Public Function SubClass_WndMessage(ByVal hWnd As _
    OLE_HANDLE,ByVal Msg As OLE_HANDLE, ByVal wParam As OLE_HANDLE, _
    ByVal lParam As Long) As Long
    If Msg <> WM_CONTEXTMENU Then
        SubClass_WndMessage = CallWindowProc(OldWinProc, _
            hWnd, Msg,wParam, lParam)
            ' 如果消息不是WM_CONTEXTMENU，就调用系统的窗口处理函数
        Exit Function
    End If
    SubClass_WndMessage = True
End Function

>>步骤4----在窗体中加入如下代码:
Private Const GWL_WNDPROC = (-4)

Private Sub Text1_MouseDown(Button As Integer, Shift As _
    Integer, X As Single, Y As Single)

    If Button = 1 Then Exit Sub
    OldWinProc = GetWindowLong(Text1.hWnd, GWL_WNDPROC)
    ' 取得窗口函数的地址
    Call SetWindowLong(Text1.hWnd, GWL_WNDPROC, AddressOf _
        SubClass_WndMessage)
        ' 用SubClass_WndMessage代替窗口函数处理消息
End Sub

Private Sub Text1_MouseUp(Button As Integer, Shift _
    As Integer, X As Single, Y As Single)
    If Button = 1 Then Exit Sub
    Call SetWindowLong(Text1.hWnd, GWL_WNDPROC, OldWinProc)
    ' 恢复窗口的默认函数
    PopupMenu a
    ' 弹出自定义菜单
End Sub

>>步骤5----编译运行,系统菜单不见了,弹出自定义菜单.