Windows 7 - Shell Extension dll Initialize method called twice on explorer left pane

Question

I have a c++ shell extension dll. The Initialize method is called twice, if I click on the explorer window left pane tree view folders. But if I click any folders on the explorer window right pane, the Initialize method called once.

The issue is my newly added menu items shows twice in the context menu, if I click on the left pane tree view.

I am wondering, is it a window functionality? I have commented all my implementation and tested with the below code:

IFACEMETHODIMP CMyContextMenu::QueryContextMenu(HMENU hmenu, UINT /*uIndex*/, UINT    cmdFirst, UINT /*uidCmdLast*/, UINT /*uFlags*/ )
{
UINT cmdId = uidCmdFirst;
OutputDebugString(L"QueryContextMenu");

    return MAKE_HRESULT ( SEVERITY_SUCCESS, FACILITY_NULL,  cmdId  - mdFirst );
}


IFACEMETHODIMP CMyContextMenu::Initialize(LPCITEMIDLIST pidlFolder, LPDATAOBJECT  pDO, HKEY /*hkeyProgID*/)
{
OutputDebugString(L"Initialize");
return S_OK;
}

When I click on left pane, the DebugViewr output is:

Initialize

QueryContextMenu

Initialize

QueryContextMenu

NoRemove Directory
{
    NoRemove Background
    {
        NoRemove ShellEx
        {
            NoRemove ContextMenuHandlers
            {
                ForceRemove myContext = s '{AE843198-3C5D-4EA6-B74F-7A41FC91D7FF}'
            }
        }
    }
}

NoRemove Directory
{
    NoRemove ShellEx
    {
        NoRemove ContextMenuHandlers
        {
            ForceRemove myContext = s '{AE843198-3C5D-4EA6-B74F-7A41FC91D7FF}'
        }
    }
}

The above registry entry is causing this issue in Win 7, If I remove "NoRemove Background", the context menu will be displayed once in tree view. But if I click on folder empty area Initialize method will not be invoked.

Answer 1

I am posting a working example from my real program (an application specific code omitted for clarity). Please try it.

STDMETHODIMP CShlExtExample::Initialize (
LPCITEMIDLIST pidlFolder, LPDATAOBJECT pDataObj, HKEY hProgID )
{
 FORMATETC fmt = { CF_HDROP, NULL, DVASPECT_CONTENT, -1, TYMED_HGLOBAL };
 STGMEDIUM stg = { TYMED_HGLOBAL };
 HDROP     hDrop;

   // Look for CF_HDROP data in the data object.
   if ( FAILED( pDataObj->GetData ( &fmt, &stg ) ))
   {
       // Return an "invalid argument" error.
       return E_INVALIDARG;
   }

   // Get a pointer to the actual data.
   hDrop = (HDROP) GlobalLock ( stg.hGlobal ); 
   if ( NULL == hDrop )
       return E_INVALIDARG;

   // Make sure there is at least one file to show menu for.
   UINT uNumFiles = DragQueryFile ( hDrop, 0xFFFFFFFF, NULL, 0 );
   HRESULT hr = S_OK;  
   if ( 0 == uNumFiles )
   {
       GlobalUnlock ( stg.hGlobal );
       ReleaseStgMedium ( &stg );
       return E_INVALIDARG;
   }

   // Application specific code.

   GlobalUnlock ( stg.hGlobal );
   ReleaseStgMedium ( &stg );

   return hr;

}

   STDMETHODIMP CShlExtExample::QueryContextMenu (
   HMENU hmenu, UINT uMenuIndex, UINT uidFirstCmd,
   UINT uidLastCmd, UINT uFlags )
   {
     // If the flags include CMF_DEFAULTONLY then do nothing.
     if ( uFlags & CMF_DEFAULTONLY )
         return MAKE_HRESULT ( SEVERITY_SUCCESS, FACILITY_NULL, 0 );

   InsertMenu ( hmenu, uMenuIndex, MF_BYPOSITION, uidFirstCmd, _T("Test Item") );

   return MAKE_HRESULT ( SEVERITY_SUCCESS, FACILITY_NULL, 1 );
   }