DOCUMENT:Q184686 27-APR-1998 [vbwin] TITLE :HOWTO: Disable the Close Option on the Control Menu of a VB Form PRODUCT :Microsoft Visual Basic for Windows PROD/VER:WINDOWS:4.0,5.0,6.0 OPER/SYS:WINDOWS KEYWORDS:kbnokeyword ====================================================================== --------------------------------------------------------------------- The information in this article applies to: - Microsoft Visual Basic Standard, Professional, and Enterprise Editions, 32-bit only, for Windows, version 4.0 - Microsoft Visual Basic Learning, Professional, and Enterprise Editions for Windows, versions 5.0, 6.0 --------------------------------------------------------------------- SUMMARY ======= To modify an item in the Visual Basic Control menu (also known as the System menu), you need to use the SetMenuItemInfo API function. This article describes how to enable/disable or check/uncheck the Close menu item in the Control menu. MORE INFORMATION ================ If you do not want the user to close a window via the Control menu or the Close box on your Form's title bar, you can disable the Close menu item on the Control menu. This method also disables double-clicking the Control box and disables the Close button on the Form's title bar. The following code sample enables/disables and checks/unchecks the Close command in the Visual Basic Control menu. Example ------- 1. Start a new standard EXE project (Form1 is added by default). 2. Add three command buttons to Form1. 3. Add the following code to Form1: Option Explicit 'Menu item constants. Private Const SC_CLOSE As Long = &HF060& 'SetMenuItemInfo fMask constants. Private Const MIIM_STATE As Long = &H1& Private Const MIIM_ID As Long = &H2& 'SetMenuItemInfo fState constants. Private Const MFS_GRAYED As Long = &H3& Private Const MFS_CHECKED As Long = &H8& 'SendMessage constants. Private Const WM_NCACTIVATE As Long = &H86 'User-defined Types. Private Type MENUITEMINFO cbSize As Long fMask As Long fType As Long fState As Long wID As Long hSubMenu As Long hbmpChecked As Long hbmpUnchecked As Long dwItemData As Long dwTypeData As String cch As Long End Type 'Declarations. Private Declare Function GetSystemMenu Lib "user32" ( _ ByVal hwnd As Long, ByVal bRevert As Long) As Long Private Declare Function GetMenuItemInfo Lib "user32" Alias _ "GetMenuItemInfoA" (ByVal hMenu As Long, ByVal un As Long, _ ByVal b As Boolean, lpMenuItemInfo As MENUITEMINFO) As Long Private Declare Function SetMenuItemInfo Lib "user32" Alias _ "SetMenuItemInfoA" (ByVal hMenu As Long, ByVal un As Long, _ ByVal bool As Boolean, lpcMenuItemInfo As MENUITEMINFO) As Long Private Declare Function SendMessage Lib "user32" Alias _ "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, _ ByVal wParam As Long, lParam As Any) As Long 'Application-specific constants and variables. Private Const xSC_CLOSE As Long = -10 Private Const SwapID As Long = 1 Private Const ResetID As Long = 2 Private hMenu As Long Private MII As MENUITEMINFO Private Sub Command1_Click() Dim Ret As Long Ret = SetId(SwapID) If Ret <> 0 Then If MII.fState = (MII.fState Or MFS_GRAYED) Then MII.fState = MII.fState - MFS_GRAYED Else MII.fState = (MII.fState Or MFS_GRAYED) End If MII.fMask = MIIM_STATE Ret = SetMenuItemInfo(hMenu, MII.wID, False, MII) If Ret = 0 Then Ret = SetId(ResetID) End If Ret = SendMessage(Me.hwnd, WM_NCACTIVATE, True, 0) SetButtons End If End Sub Private Sub Command2_Click() Dim Ret As Long If MII.fState = (MII.fState Or MFS_CHECKED) Then MII.fState = MII.fState - MFS_CHECKED Else MII.fState = (MII.fState Or MFS_CHECKED) End If MII.fMask = MIIM_STATE Ret = SetMenuItemInfo(hMenu, MII.wID, False, MII) SetButtons End Sub Private Sub Command3_Click() Unload Me End Sub Private Function SetId(Action As Long) As Long Dim MenuID As Long Dim Ret As Long MenuID = MII.wID If MII.fState = (MII.fState Or MFS_GRAYED) Then If Action = SwapID Then MII.wID = SC_CLOSE Else MII.wID = xSC_CLOSE End If Else If Action = SwapID Then MII.wID = xSC_CLOSE Else MII.wID = SC_CLOSE End If End If MII.fMask = MIIM_ID Ret = SetMenuItemInfo(hMenu, MenuID, False, MII) If Ret = 0 Then MII.wID = MenuID End If SetId = Ret End Function Private Sub SetButtons() If MII.fState = (MII.fState Or MFS_GRAYED) Then Command1.Caption = "Enable" Else Command1.Caption = "Disable" End If If MII.fState = (MII.fState Or MFS_CHECKED) Then Command2.Caption = "Uncheck" Else Command2.Caption = "Check" End If End Sub Private Sub Form_Load() Dim Ret As Long hMenu = GetSystemMenu(Me.hwnd, 0) MII.cbSize = Len(MII) MII.dwTypeData = String(80, 0) MII.cch = Len(MII.dwTypeData) MII.fMask = MIIM_STATE MII.wID = SC_CLOSE Ret = GetMenuItemInfo(hMenu, MII.wID, False, MII) SetButtons Command3.Caption = "Exit" End Sub 4. Press F5 to run the program. Additional Notes ---------------- Visual Basic handles enabling and disabling the standard Control menu items, including Restore, Size, Move, Minimize, and Maximize (the Close menu is always enabled). Generally, Visual Basic enables/disables the menu items depending on the window's state (minimized, maximized, or normal) by referencing these menu items by their menu item IDs. As a result, if we merely add or remove MFS_GRAYED from a menu's fState, Visual Basic immediately resets it. The workaround is to change the menu item's ID (which also renders the item inoperable). Using this workaround, we can effectively disable a menu item that Visual Basic intends to be enabled, but we cannot enable a menu item Visual Basic intends to be disabled (the menu item must have its regular ID to be operable). Enabling a menu item that Visual Basic intends to be disabled requires removing the item and replacing it with a menu item of our own (this is not covered in this article). When the Close menu item is enabled or disabled, the Close box on the title bar should also be normal or grayed, respectively. Sending the message WM_NCACTIVATE (nonclient activate) notifies the window to refresh its title bar so the Close box is updated to appear normal or grayed. Additional Constants -------------------- 'Menu item constants Const SC_SIZE As Long = &HF000& Const SC_SEPARATOR As Long = &HF00F& Const SC_MOVE As Long = &HF010& Const SC_MINIMIZE As Long = &HF020& Const SC_MAXIMIZE As Long = &HF030& Const SC_CLOSE As Long = &HF060& Const SC_RESTORE As Long = &HF120& 'SetMenuItemInfo fMask Constants Const MIIM_STATE As Long = &H1& Const MIIM_ID As Long = &H2& Const MIIM_SUBMENU As Long = &H4& Const MIIM_CHECKMARKS As Long = &H8& Const MIIM_TYPE As Long = &H10& Const MIIM_DATA As Long = &H20& Related APIs ------------ SetMenuDefaultItem -- You must disable Close to use this in Visual Basic HiliteMenuItem REFERENCES ========== For the 16-bit equivalent, please see the following article in the Microsoft Knowledge Base: ARTICLE-ID: Q82876 TITLE : How to Disable Close Command in VB Control Menu (System Menu) Additional query words: ====================================================================== Keywords : kbnokeyword Version : WINDOWS:4.0,5.0,6.0 Platform : WINDOWS Issue type : kbhowto ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. 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