The information in this article applies to:
- The Microsoft Foundation Classes (MFC) included with:
- Microsoft Visual C++ for Windows, versions 1.0, 1.5, 1.51, 1.52
- Microsoft Visual C++ 32-bit Edition, 2.0, 2.1, 4.0, 5.0
SUMMARY
There are two ways to remove the system menu of an application when a user
clicks an iconized application:
- 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.
- 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
To remove the system menu completely from the application, override
the main frame window's PreCreateWindow method as follows:
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
The following steps and code fragments show how to remove the system menu
when a user clicks an iconized application. The system menu is restored
when the application is not iconized.
- 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
.
}
- 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
.
}
- 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) && (!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);
}
}
}
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