DOCUMENT:Q224302  11-JAN-2001  [vbwin]
TITLE   :HOWTO: Suppress a TextBox Control's Popup Menu
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER:WINDOWS:5.0,6.0
OPER/SYS:
KEYWORDS:kbAPI kbGrpDSUser kbVBp500 kbVBp600 kbWndwMsg kbGrpDSVB kbCodeSnippet

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The information in this article applies to:

 - Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0 
 - Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0 
 - Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0 
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SUMMARY
=======

When a user right clicks a textbox, the standard textbox popup menu appears.
This article demonstrates how to suppress the textbox popup menu.

MORE INFORMATION
================

When a user right clicks a textbox, the textbox window receives a WM_CONTEXTMENU
message. When the WM_CONTEXTMENU message is received, the textbox window shows
the popup menu. A window procedure can capture all WM_CONTEXTMENU messages sent
to a textbox window, thus suppressing the default popup window.

WARNING: This sample replaces the WindowProc of the text box window using a
technique called a hook. Failure to unhook a window before its imminent
destruction results in application errors, invalid page faults, and data loss.
This is due to the fact that the new WindowProc function being pointed to no
longer exists, but the window has not been notified of the change. Always unhook
the sub-classed window upon unloading the sub-classed form or exiting the
application. This is especially important while debugging an application that
uses this technique within the Microsoft Visual Basic Development Environment.
Pressing the END button on the toolbar or selecting End from the Run menu
without unhooking will cause an invalid page fault and close Microsoft Visual
Basic.

NOTE: This functionality is not available in any release of Microsoft Visual
Basic for Applications (VBA) prior to Microsoft Office 2000.

Step-by-Step Example
--------------------

1. Start a new Visual Basic Standard EXE project. Form1 is created by default.

2. Add two text boxes to Form1.

3. Add a standard module to the project.

4. Add the following code to the General Declarations section of Module1:

   Option Explicit

   Public Declare Function SetWindowLong Lib "user32" Alias _
      "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, _
      ByVal dwNewLong As Long) As Long
    
   Public 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 Const GWL_WNDPROC = (-4)

   Public Const WM_CONTEXTMENU = &H7B

   Global lpPrevWndProc As Long
   Global gHW As Long

   Public Sub Hook()
      lpPrevWndProc = SetWindowLong(gHW, GWL_WNDPROC, _
      AddressOf gWindowProc)
   End Sub

   Public Sub Unhook()
      Dim temp As Long
      temp = SetWindowLong(gHW, GWL_WNDPROC, lpPrevWndProc)
   End Sub

   Public Function gWindowProc(ByVal hWnd As Long, ByVal Msg As Long, _
                    ByVal wParam As Long, ByVal lParam As Long) As Long
      If Msg = WM_CONTEXTMENU Then
         Debug.Print "Intercepted WM_CONTEXTMENU at " & Now
         gWindowProc = True
      Else ' Send all other messages to the default message handler
         gWindowProc = CallWindowProc(lpPrevWndProc, hWnd, Msg, wParam, _
            lParam)
      End If
   End Function

5. Add the following code to the General Declarations section of Form1:

   Private Sub Form_Load()
      gHW = Text1.hwnd
      Hook
   End Sub

   Private Sub Form_Unload(Cancel As Integer)
      Unhook
   End Sub

6. Run the project. Right-click Text1. No popup menu appears. Right-click Text2
   and the standard popup menu appears.

REFERENCES
==========

For additional information, please see the following articles in the Microsoft
Knowledge Base:

   Q168795 HOWTO: Hook Into a Window's Messages Using AddressOf

   Q170570 HOWTO: Build a Windows Message Handler with AddressOf in VB

"Dan Appleman's Visual Basic Programmer's Guide to the Win32 API" by Dan
Appleman

Platform Software Development Kit (SDK) Online Help

Additional query words:

======================================================================
Keywords          : kbAPI kbGrpDSUser kbVBp500 kbVBp600 kbWndwMsg kbGrpDSVB kbCodeSnippet 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600
Version           : WINDOWS:5.0,6.0
Issue type        : kbhowto

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Copyright Microsoft Corporation 2001.