DOCUMENT:Q185451 11-JAN-2001 [vbwin] TITLE :HOWTO: Display Descriptions of Menu Items When Highlighted PRODUCT :Microsoft Visual Basic for Windows PROD/VER:WINDOWS:5.0,6.0 OPER/SYS: KEYWORDS:kbAPI kbMenu kbVBp500 kbVBp600 kbOSWin32s ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Visual Basic Learning Edition for Windows, version 6.0 - Microsoft Visual Basic Professional Edition for Windows, version 6.0 - Microsoft Visual Basic Enterprise Edition for Windows, version 6.0 - Microsoft Visual Basic Control Creation Edition for Windows, version 5.0 - Microsoft Visual Basic Learning Edition for Windows, version 5.0 - Microsoft Visual Basic Professional Edition for Windows, version 5.0 - Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 ------------------------------------------------------------------------------- SUMMARY ======= Some applications, such as the Windows Explorer, provide a description of each menu item in the status bar when the menu item is highlighted. This functionality provides the user more information about what each menu command does before it is activated. This article shows you how to use several of the Windows API functions to include this functionality in your Visual Basic application. MORE INFORMATION ================ The following steps demonstrate how to create a sample application that provides descriptions for menu items when the menu items are highlighted. To achieve this functionality, you must use a concept known as subclassing to allow you to detect when the WM_MENUSELECT message occurs. This message occurs whenever a menu selection is either highlighted or not highlighted. For more information on subclassing, please see the following article in the Microsoft Knowledge Base: Q168795 HOWTO: Hook Into a Window's Messages Using AddressOf NOTE: Failure to unhook a window before its destruction results in application errors, Invalid Page Faults, or data loss. This occurs because the new WindowProc function that is being pointed to no longer exists, but the window has not been notified of the change. Always unhook the subclassed window upon unloading the subclassed form or exiting the application. This is especially important when you use Visual Basic to debug an application that includes subclassing. Pressing the End button or selecting End from the Run menu without unhooking causes an Invalid Page Fault and closes Microsoft Visual Basic. Steps to Create Sample Application ---------------------------------- 1. Create a new Standard EXE project. 2. Create the following menu on Form1 using the Menu Editor: Menu Caption Menu Name ----------- --------- File mnuFile New mnuNew Open mnuOpen Close mnuClose Edit mnuEdit Cut mnuCut Copy mnuCopy Paste mnuPaste Normal mnuPasteNormal Special mnuPasteSpecial NOTE: You should create the menu captions exactly as shown. If you choose to add accelerators, you need to modify the following code to reflect these changes to your captions. 3. Paste the following code into the code window for Form1: Option Explicit Private Sub Form_Load() 'Store a handle to this form. gHW = Me.hwnd 'Call this Sub procedure to begin hooking into messages. Hook End Sub Private Sub Form_Unload(Cancel As Integer) 'Call this Sub procedure to cease hooking into messages. Unhook End Sub 4. Add a standard module to the project. 5. Paste the following code into the module: Option Explicit 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 Private Declare Function SetWindowLong Lib "user32" _ Alias "SetWindowLongA" (ByVal hwnd As Long, _ ByVal nIndex As Long, ByVal dwNewLong As Long) As Long Private Declare Function GetMenu Lib "user32" _ (ByVal hwnd As Long) As Long Private Declare Function GetSubMenu Lib "user32" _ (ByVal hMenu As Long, ByVal nPos As Long) As Long Private Declare Function GetMenuItemCount Lib "user32" _ (ByVal hMenu As Long) As Long Private Declare Function GetMenuState Lib "user32" _ (ByVal hMenu As Long, ByVal wID As Long, _ ByVal wFlags As Long) As Long Private Declare Function GetMenuString Lib "user32" _ Alias "GetMenuStringA" (ByVal hMenu As Long, _ ByVal wIDItem As Long, ByVal lpString As String, _ ByVal nMaxCount As Long, ByVal wFlag As Long) As Long Private Const MF_BYPOSITION = &H400& Private Const MF_HILITE = &H80& Private Const WM_MENUSELECT = &H11F Private Const GWL_WNDPROC = -4 Public lpPrevWndProc As Long Public gHW As Long Public Sub Hook() 'Begin hooking into messages. lpPrevWndProc = SetWindowLong(gHW, GWL_WNDPROC, _ AddressOf WindowProc) End Sub Public Sub Unhook() 'Cease hooking into messages. SetWindowLong gHW, GWL_WNDPROC, lpPrevWndProc End Sub Function AnyLit(hSubSubMenu As Long) As Long Dim i As Long Dim MenuCount As Long 'Get the number of items in the menu. MenuCount = GetMenuItemCount(hSubSubMenu) 'Loop through the menu items. For i = 0 To MenuCount - 1 'Check whether this item is highlighted. If GetMenuState(hSubSubMenu, i, MF_BYPOSITION) And _ MF_HILITE Then AnyLit = True Exit Function End If Next i 'Return FALSE, no items highlighted. AnyLit = False End Function Private Sub WalkSubMenu(hSubMenu As Long) Dim i As Long Dim MenuItems As Long Dim hSubSubMenu As Long Dim buffer As String Dim result As Long 'Get the count of menu items in this menu. MenuItems = GetMenuItemCount(hSubMenu) 'Loop through all the items on the menu. For i = 0 To MenuItems - 1 'Determine whether this item is highlighted. If GetMenuState(hSubMenu, i, MF_BYPOSITION) And _ MF_HILITE Then 'Attempt to get a submenu for each menu item. hSubSubMenu = GetSubMenu(hSubMenu, i) 'Check for a submenu with something selected on it. If hSubSubMenu And AnyLit(hSubSubMenu) Then 'There is a submenu with a selection so walk it. WalkSubMenu hSubSubMenu Else 'This is it. 'Set buffer size. buffer = Space(255) 'Call the API to get the caption for the menu item. result = GetMenuString(hSubMenu, i, buffer, _ Len(buffer), MF_BYPOSITION) 'Trim the buffer of extra characters. buffer = Left$(buffer, result) 'Set the caption of the form to a description of the 'menu item. Form1.Caption = GetDescription(buffer) 'Exit this Sub procedure. Exit Sub End If End If Next i End Sub Public Sub FindHilite(TheForm As Form) Dim hMenu As Long Dim hSubMenu As Long Dim i As Long Dim MenuCount As Long 'Clear any previous description. Form1.Caption = "" 'Get the menu handle. hMenu = GetMenu(TheForm.hwnd) 'Check to see if there is no menu. If hMenu <> 0 Then 'Get the number of top-level menus. MenuCount = GetMenuItemCount(hMenu) 'Enumerate through all top-level menus. For i = 0 To MenuCount - 1 'Ignore top-level menus not currently selected. If GetMenuState(hMenu, i, MF_BYPOSITION) And _ MF_HILITE Then 'Get a handle to the submenu. hSubMenu = GetSubMenu(hMenu, i) 'Walk the submenu. WalkSubMenu hSubMenu End If Next i End If End Sub Private Function GetDescription(MenuCaption As String) As String 'Determine the description of the menu item. Select Case MenuCaption Case "New" GetDescription = "Creates a new document" Case "Open" GetDescription = "Opens a Document" Case "Close" GetDescription = "Closes Document" Case "Cut" GetDescription = "Cuts Selection to Clipboard" Case "Copy" GetDescription = "Copies Selection to Clipboard" Case "Paste" GetDescription = "Pastes Contents of Clipboard" Case "Normal" GetDescription = "Regular Paste" Case "Special" GetDescription = "Special Paste" Case Else GetDescription = "" End Select End Function Function WindowProc(ByVal hw As Long, ByVal uMsg As Long, _ ByVal wParam As Long, ByVal lParam As Long) As Long 'Check for a menu selection message. If uMsg = WM_MENUSELECT Then FindHilite Form1 End If 'Pass the message to Windows for processing. WindowProc = CallWindowProc(lpPrevWndProc, hw, uMsg, _ wParam, lParam) End Function 6. Click Start or click the F5 key to start the program. Open various menu items and observe the changes that occur to the form's caption. Additional query words: Hook Subclass ====================================================================== Keywords : kbAPI kbMenu kbVBp500 kbVBp600 kbOSWin32s Technology : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500Search kbVBA500 kbVBA600 kbVB500 kbVB600 kbZNotKeyword3 Version : WINDOWS:5.0,6.0 Issue type : kbhowto ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2001.