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Q299853: HOWTO: Modify the Default Web Browser and E-mail Client

Article: Q299853
Product(s): Microsoft Visual Basic for Windows
Version(s): 5.0,6.0
Operating System(s): 
Keyword(s): kbAPI kbVBp kbGrpDSVB kbDSupport
Last Modified: 13-JUL-2001

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The information in this article applies to:

- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0, used with:
   - the operating system: Microsoft Windows XP 
- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0, used with:
   - the operating system: Microsoft Windows XP 
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This article discusses a Beta release of a Microsoft product. The 
information in this article is provided as-is and is subject to change
without notice.

No formal product support is available from Microsoft for this Beta 
product. For information about obtaining support for a Beta release, 
please see the documentation included with the Beta product files, or 
check the Web location from which you downloaded the release.

SUMMARY
=======

On a Windows XP-based computer, Windows XP sets the default Start menu Internet
browser to Microsoft Internet Explorer and e-mail client to Microsoft Outlook
Express. The Start menu Internet browser only controls the application that is
started when you click the Internet or E-mail icon on the Start menu. This is
separate from the default Web browser or e-mail client that is used to start
arbitrary URLs from anywhere in the system. You can programmatically change the
defaults for the system or individually for each user.

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

By default, Windows XP uses a global setting in the HKeyLocalMachine (HKLM)
Registry key to set an initial, default e-mail and Web browser client from the
Start menu. Windows XP also implements new registry keys in HKeyCurrentUser
(HKCU) to store individual internet and e-mail client information for each user
as part of their profile if users select a different client than the default.
The following code sample adds a Web browsing and e-mail client to the available
options on the system and shows how to modify both the global and the current
user:

  Const REG_SZ As Long = 1
  Const HKEY_CURRENT_USER = &H80000001
  Const HKEY_LOCAL_MACHINE = &H80000002
  Const KEY_SET_VALUE = &H2
  Const KEY_ALL_ACCESS = &H3F
  Const REG_OPTION_NON_VOLATILE = 0
  Const HWND_BROADCAST = &HFFFF
  Const WM_SETTINGCHANGE = &H1A

  Declare Function RegCloseKey Lib "advapi32.dll" _
    (ByVal hKey As Long) As Long
  Declare Function RegCreateKeyEx Lib "advapi32.dll" _
    Alias "RegCreateKeyExA" (ByVal hKey As Long, _
    ByVal lpSubKey As String, ByVal Reserved As Long, _
    ByVal lpClass As String, ByVal dwOptions As Long, _
    ByVal samDesired As Long, ByVal lpSecurityAttributes As Long, _
    phkResult As Long, lpdwDisposition As Long) As Long
  Declare Function RegOpenKeyEx Lib "advapi32.dll" _
    Alias "RegOpenKeyExA" (ByVal hKey As Long, _
    ByVal lpSubKey As String, ByVal ulOptions As Long, _
    ByVal samDesired As Long, phkResult As Long) As Long
  Declare Function RegSetValueExString Lib "advapi32.dll" _
    Alias "RegSetValueExA" (ByVal hKey As Long, _
    ByVal lpValueName As String, ByVal Reserved As Long, _
    ByVal dwType As Long, ByVal lpValue As String, _
    ByVal cbData As Long) As Long
  Declare Function SendMessage Lib "user32" _
    Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, _
    ByVal wParam As Long, lparam As String) As Long
  Public Function SetClient(iClient As Integer, sDisplayName As String, _
    sClientCommandLine As String, sClientResourceDLL As String, _
    iLocalization As Integer, bGlobalClient As Boolean, _
    Optional sCLParameters As String, Optional bMakeDefault As Boolean) As Integer
    
    ' iClient - 1 for internet browser, 2 for e-mail client
    ' sDisplayName - the name to be displayed on the menu for the client
    ' sClientCommandLine - the path and filename of the e-mail client
    '
    ' The next two parameters are included for localization of the client.
    ' For backwards compatibility with applications that do not support localized
    ' strings, the name of the application in the installed language should be set
    ' as the Default value for the key.
    ' sClientResourceDLL - provides a path to an EXE or DLL containing the
    '   localized strings for the client.
    ' iLocalization - a string resource ID within the DLL whose value is
    '   to be displayed to the user allowing the same registration to
    '   be used for multiple languages.  For each language, provide a
    '   different Resource DLL, and the dynamic loading of the string
    '   from the DLL results in the correct strings being displayed, depending
    '   on the language.
    '
    ' bGlobalClient - sets the value for either all users (True) or the
    '   current user (False)
    ' sCLParameters - additional parameters on the command line to be passed to the
    '   browser or e-mail client.
    ' bMakeDefault - (Optional) set the browser or e-mail application as the default
    
    Dim iStatus As Integer
    Dim hHandle As Long
    Dim hGRegKey As String
    Dim hLRegKey As String
    Dim sCommand As String
    Dim sKey As String
    Dim sAll As String
    Dim sRoot As String
    Dim hKey As Long
    Dim sLoc As String
    hGRegKey = HKEY_LOCAL_MACHINE
    hLRegKey = HKEY_CURRENT_USER
    
    If iClient = 1 Then
      sRoot = "Software\Clients\StartMenuInternet"
    Else
      sRoot = "Software\Clients\Mail"
    End If
    
    ' Create and null terminate needed strings
    sCommand = "shell\open\command"
    sKey = sRoot & "\" & sDisplayName
    sAll = sKey & "\" & sCommand
    sLoc = "@" & sClientResourceDLL & "," & iLocalization & Chr$(0)
    sClientLocation = """" & sClientCommandLine & """" & _
      IIf(sCLParameters <> "", " ", "") & Trim(sCLParameters) & Chr$(0)
    sDisplayName = sDisplayName & Chr$(0)
    
    ' Create a registry key for the new client
    iStatus = RegCreateKeyEx(hGRegKey, sKey, 0&, vbNullString, _
      REG_OPTION_NON_VOLATILE, KEY_ALL_ACCESS, 0&, hNewKey, lRetVal)
    iStatus = RegCreateKeyEx(hGRegKey, sAll, 0&, vbNullString, _
      REG_OPTION_NON_VOLATILE, KEY_ALL_ACCESS, 0&, hNewKey, lRetVal)
    If iStatus = ERROR_NONE Then
      iStatus = RegOpenKeyEx(hGRegKey, sAll, 0, KEY_SET_VALUE, hKey)
      iStatus = RegSetValueExString(hKey, "", 0&, REG_SZ, sClientLocation, _
        Len(sClientLocation))
      iStatus = RegCloseKey(hKey)
      iStatus = RegOpenKeyEx(hGRegKey, sKey, 0, KEY_SET_VALUE, hKey)
      iStatus = RegSetValueExString(hKey, "", 0&, REG_SZ, sDisplayName, _
        Len(sDisplayName))
      ' Add the localization string
      iStatus = RegSetValueExString(hKey, "LocalizedString", 0&, REG_SZ, _
          sLoc, Len(sLoc))
      iStatus = RegCloseKey(hKey)
    Else
      SetClient = iStatus
      Exit Function
    End If
    
    '  Sets browser as local or global default if specified
    If bMakeDefault Then
      If bGlobalClient Then
        iStatus = RegOpenKeyEx(hGRegKey, sRoot, 0, KEY_SET_VALUE, hKey)
        iStatus = RegSetValueExString(hKey, "", 0&, REG_SZ, sDisplayName, _
          Len(sDisplayName))
        iStatus = RegCloseKey(hKey)
      Else
        iStatus = RegCreateKeyEx(hLRegKey, sRoot, 0&, vbNullString, _
          REG_OPTION_NON_VOLATILE, KEY_ALL_ACCESS, 0&, hNewKey, lRetVal)
        iStatus = RegSetValueExString(hNewKey, "", 0&, REG_SZ, _
          sDisplayName, Len(sDisplayName))
        iStatus = RegCloseKey(hNewKey)
      End If
      UpdateMenus
    End If
  End Function
  Private Sub UpdateMenus()
    ' Refresh the menu choices with the updated client
    Dim iRetVal As Integer
    iRetVal = SendMessage(HWND_BROADCAST, WM_SETTINGCHANGE, 0, _
      "SOFTWARE\Clients\mail")
    iRetVal = SendMessage(HWND_BROADCAST, WM_SETTINGCHANGE, 0, _
      "SOFTWARE\Clients\StartMenuInternet")
  End Sub

Here are some examples of calling this function:

  Dim x As Integer
  '  Sets up a browser for the current user and makes it default
  x = SetClient(1, "My Browser", "C:\Program Files\MyBrowser\mybrowser.exe", "C:\Program Files\MyBrowser\localization.dll", -123, True, "-homepage", False)
  '  Sets up an e-mail client for the current user and makes it default
  x = SetClient(2, "My E-mail", "C:\Program Files\MyEmail\myemail.exe", "C:\Program Files\MyEmail\localization.dll", -456, True, "-inbox", False)

REFERENCES
==========

For additional information, click the article numbers below to view the articles
in the Microsoft Knowledge Base:

  Q145679 HOWTO: Use the Registry API to Save and Retrieve Setting

  Q297878 BETA-HOWTO: Register an Internet Browser or E-mail Client With the
  Windows XP Start Menu

Additional query words:

======================================================================
Keywords          : kbAPI kbVBp kbGrpDSVB kbDSupport 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2
Version           : :5.0,6.0
Issue type        : kbhowto

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