HOWTO: Remove the System Menu from an Iconized Application

• The Microsoft Foundation Classes (MFC), used with:
  • Microsoft Visual C++ for Windows, 16-bit edition, versions 1.0, 1.5, 1.51, 1.52
  • Microsoft Visual C++, 32-bit Editions, versions 2.0, 2.1, 4.0, 5.0, 6.0

SUMMARY

There are two ways to remove the system menu of an application when a user clicks an iconized application:

1. Override the main frame window's PreCreateWindow function to remove the WS_SYSMENU from the window's style field. However, this method removes the system menu altogether from the application.



2. Override the main frame window's OnSize method, and change the window style of the mainframe to either include or exclude the WS_SYSMENU style bit depending on user action. Use this technique if the user wants to remove the system menu when the application is iconized and add the system menu back to the application when the application is restored.

MORE INFORMATION

Method One

   BOOL CMainFrame::PreCreateWindow(CREATESTRUCT & cs)
   {
           // Call the base class version of PreCreateWindow, replace
          //  CMDIFrameWnd with CFrameWnd in the following line
          //  for an SDI application

           if (!CMDIFrameWnd::PreCreateWindow(cs))
                return FALSE;

          // Remove the system menu style bit from the window

           cs.style &= ~WS_SYSMENU;
           return TRUE;
   } 

Method Two

1. Declare a BOOLEAN public data member in the class declaration of CMainFrame. This data member determines if the system menu is enabled or not:

   
         // In an SDI application CMainFrame will be derived from CFrameWnd
   
         class CMainFrame : public CMDIFrameWnd
         {
         public:
            BOOL sys_menu_enabled;
                .
                .  // Existing class declarations
                .
         } 




2. Modify the CMainFrame constructor to initialize the sys_menu_enabled data member function to TRUE:

   
         CMainFrame::CMainFrame()
         {
           //default the system menu to be enabled
           sys_menu_enabled = TRUE;
                .
                .  // Continue with normal constructor code, if any
                .
         } 




3. Use the Class Wizard to create a message handler for the WM_SIZE message for the CMainFrame class, and add the following code to the CMainFrame::OnSize message handler:

   
         void CMainFrame::OnSize(UINT nType, int cx, int cy)
         {
           // declare a local variable to hold the window style
   
              long window_style;
   
           //call base class's OnSize function,
           //If SDI application call CFrameWnd::OnSize()
   
           CMDIFrameWnd::OnSize(nType, cx, cy);
   
           //if user is minimizing or iconizing the application
   
           if (nType == SIZE_MINIMIZED)
           {
                // Get the main frame window's style
                 window_style = GetWindowLong(m_hWnd, GWL_STYLE);
   
                //Remove the system menu from the window's style
                 window_style &= ~WS_SYSMENU;
   
                //toggle the boolean data member to show sys menu disabled
                 sys_menu_enabled = FALSE;
   
                //set the style attribute of the main frame window
                SetWindowLong(m_hWnd, GWL_STYLE, window_style);
           }
           else
           {
                //if user is restoring the application and his system menu
                //is disabled,
                if ((nType == SIZE_RESTORED) || nType == SIZE_MAXIMIZED) &&
                   (!sys_menu_enabled))
                {
                    window_style = GetWindowLong(m_hWnd, GWL_STYLE);
   
                  //Add the system menu to the window's style
                    window_style |= WS_SYSMENU;
   
                 //toggle the boolean data member to show sys menu enabled
                   sys_menu_enabled = TRUE;
   
                   SetWindowLong(m_hWnd, GWL_STYLE, window_style);
                   SendMessage(WM_NCACTIVATE,TRUE);
                }
            }
         } 

Additional query words:

Keywords : kbcode kbMFC KbUIDesign kbVC kbVC100 kbVC150 kbVC200 kbVC210 kbVC400 kbVC500 kbVC600
Version : winnt:2.0,2.1,4.0,5.0,6.0
Platform : winnt
Issue type : kbhowto