Sample Download: http://code.msdn.microsoft.com/CSCustomizeSysMenu-024ccb7f

Today’s code sample demonstrates how to modify a Windows Forms application’s system menu

The sample was written by the Microsoft engineer Nibu Babu Thomas.

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Introduction

This application demonstrates how to modify a Windows Forms application’s system menu.

Running the Sample

This is how the application looks like…

Using the Code

In this application I’ve demonstrated how to do the following actions…

1. Retrieve system menu: refer btnAddToFormSystemMenu_Click
2. Modify system menu: refer btnAddToFormSystemMenu_Click
3. Retrieve text item of a system menu item: refer handleSysCustomCommand

How to handle events from system menu items: refer WndProc

The gist of the application lies in the following functions…

private void btnAddToFormSystemMenu_Click(object sender, EventArgs e) 
{ 
    IntPtr hMenu = GetSystemMenu(this.Handle, false); 
    if (hMenu != IntPtr.Zero) 
    { 
        Int32 Count             = GetMenuItemCount(hMenu); 
        MENUITEMINFO mnuInfo    = new MENUITEMINFO(); 
        mnuInfo.cbSize          = MENUITEMINFO.sizeOf; 
        mnuInfo.fMask           = MIIM_STRING | MIIM_ID; 
        mnuInfo.fState          = MFS_ENABLED; 
        mnuInfo.fType           = MFT_STRING; 
        mnuInfo.wID             = BaseCommandId + ++CurrentIndex; 
        mnuInfo.dwTypeData      = txtMenuCaption.Text; 
        InsertMenuItem(hMenu, (UInt32)Count, true, ref mnuInfo); 
        DrawMenuBar(hMenu); 
    } 
} 

private void handleSysCustomCommand(UInt32 CmdId) 
{ 
    IntPtr hMenu = GetSystemMenu(this.Handle, false); 
    MENUITEMINFO mnuInfo = new MENUITEMINFO(); 
    mnuInfo.cbSize = MENUITEMINFO.sizeOf; 
    mnuInfo.fType = MFT_STRING; 
    mnuInfo.fMask = MIIM_STRING; 
  
    // Get size of buffer first, this call will fill out mnuInfo.cch val which is the buffere size 
    if (!GetMenuItemInfo(hMenu, CmdId, false, ref mnuInfo)) 
    { 
        ShowLastError(); 
    } 
    else 
    { 
        // Pad up a bit 
        mnuInfo.cch += 4;  
        mnuInfo.dwTypeData = new String(' ', (Int32)mnuInfo.cch); 
        if(!GetMenuItemInfo(hMenu, CmdId, false, ref mnuInfo)) // This time get menu item text 
        { 
            ShowLastError(); 
        } 
        else 
        { 
            String Text = String.Format("You clicked on: {0}", mnuInfo.dwTypeData); 
            MessageBox.Show(Text, "Menu text", MessageBoxButtons.OK, MessageBoxIcon.Information); 
        } 
    } 
} 
  
// A demo on how to handle the event from the new system menu items... 
protected override void WndProc(ref Message Msg) 
{ 
    if (Msg.Msg == WM_SYSCOMMAND) 
    { 
        if ((UInt32)Msg.WParam.ToInt32() > BaseCommandId) 
        { 
            handleSysCustomCommand((UInt32)Msg.WParam.ToInt32()); 
        } 
    } 
    base.WndProc(ref Msg); 
} 

More Information

GetSystemMenu function
http://msdn.microsoft.com/en-us/library/windows/desktop/ms647985(v=vs.85).aspx

GetMenuItemInfo function
http://msdn.microsoft.com/en-us/library/windows/desktop/ms647980(v=vs.85).aspx

GetMenuItemCount
http://msdn.microsoft.com/en-us/library/windows/desktop/ms647978(v=vs.85).aspx

DrawMenuBar function
http://msdn.microsoft.com/en-us/library/windows/desktop/ms647633(v=vs.85).aspx

GetMenuItemID function
http://msdn.microsoft.com/en-us/library/windows/desktop/ms647979(v=vs.85).aspx

GetMenuInfo function
http://msdn.microsoft.com/en-us/library/windows/desktop/ms647977(v=vs.85).aspx