• Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, version 6.0
• Microsoft Visual Basic Control Creation, Learning, Professional, and Enterprise Editions for Windows, version 5.0
• Microsoft Visual Basic Standard, Professional, and Enterprise Editions, 32-bit only, for Windows, version 4.0
• Microsoft Access versions 7.0, 97

SUMMARY

When trying to determine whether a child window of an application is open, you need to know whether it is a child of the main application window, a grandchild, or an independent window. This article provides a method of creating a hierarchical listing of all currently open windows and their window class names, making it easier navigating a program's window hierarchy.

MORE INFORMATION

WARNING: Microsoft provides code examples for illustration only, without warranty either expressed or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose. This code is provided 'as is' and Microsoft does not guarantee that the following code can be used in all situations. Microsoft does not support modifications of the code to suit customer requirements for a particular purpose.

Step-by-Step Example

1. Create a new project with a Form and a Module.
   
   
2. Add the following controls to the form:

      Control            Name         Property   Value
      ------------------------------------------------
      Command button     Command1
      Text box           Text1        MultiLine  TRUE
      Text box           Text1        Scrollbars 2- Vertical
    

   NOTE: The MultiLine property only applies to Visual Basic.
   
   
3. Type the following code into the module:

         Option Explicit
   
         Public Const GW_CHILD = 5
         Public Const GW_HWNDNEXT = 2
   
         Declare Function GetWindow Lib "user32" (ByVal hwnd As Long, _
                 ByVal wCmd As Long) As Long
         Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" _
                 (ByVal hwnd As Long, ByVal lpString As String, _
                 ByVal cch As Long) As Long
         Declare Function GetTopWindow Lib "user32" _
                 (ByVal hwnd As Long) As Long
         Declare Function GetClassName Lib "user32" Alias "GetClassNameA" _
                 (ByVal hwnd As Long, ByVal lpClassName As String, _
                 ByVal nMaxCount As Long) As Long
    

   
   
   
4. Add the following code to the form's module:

         Sub AddChildWindows(ByVal hwndParent As Long, ByVal Level As Long)
         Dim WT As String, CN As String, Length As Long, hwnd As Long
           If Level = 0 Then
             hwnd = hwndParent
           Else
             hwnd = GetWindow(hwndParent, GW_CHILD)
           End If
           Do While hwnd <> 0
             WT = Space(256)
             Length = GetWindowText(hwnd, WT, 255)
             WT = Left$(WT, Length)
             CN = Space(256)
             Length = GetClassName(hwnd, CN, 255)
             CN = Left$(CN, Length)
             Me!Text1 = Me!Text1 & vbCrLf & String(2 * Level, ".") _
                      & WT & " (" & CN & ")"
             AddChildWindows hwnd, Level + 1
             hwnd = GetWindow(hwnd, GW_HWNDNEXT)
           Loop
         End Sub
   
         Sub Command1_Click()
         Dim hwnd As Long
           hwnd = GetTopWindow(0)
           If hwnd <> 0 Then
             AddChildWindows hwnd, 0
           End If
         End Sub
    

   
   
   
5. Visual Basic only: Run the project.
   
   Access only: Open the form.
   
   
6. Click the CommandButton. The text box will be filled with a list of windows and their children arranged in a hierarchical order. The class name will follow the window name, such as:

         MainWindowName (WindowClass)
         ..ChildWindowName (WindowClass)
         ....GrandchildWindowName (WindowClass)
    

   
   
   

REFERENCES

Microsoft Windows SDK

Additional query words: kbVBp500 kbVBp600 kbdse kbDSupport kbVBp kbWinAPI

Keywords : kbGrpVBDB
Issue type : kbhowto
Technology :

Article ID: Q168829

Last Reviewed:
February 16, 2000

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