Refreshing a folder that doesn't exist in the file system - winapi

Question

In my shell extension I have folders that don't actually exist in the file system, but only appear so to the user.
When the content of those folders is changed, I want to refresh them, and currently I do it in the same method I do for regular folders:
Win32.SHChangeNotify(SHCNE_UPDATEDIR, SHCNF_IDLIST | SHCNF_FLUSH, PIDL, IntPtr.Zero);
Whereas PIDL is a list of shell folders IDs, as required by SHCNF_IDLIST.
The problem is that explorer doesn't handle my non existing folders. Instead of refreshing them, it sends me back to the root folder.
I know that I construct the PIDL correctly since this mechanism works for existing folders, as previously mentioned.
How can I override the handler to SHChangeNotify? Or is there a better way for calling refresh?
Edit:
How my PIDL is generated:
IntPtr GetPIDL(IFolderItem target)
{
Stack stack = new Stack(5);
IntPtr data = IntPtr.Zero;
byte[] rootPIDL = null;
IFolderItem curr = target;
while (curr != null)
{
if (curr.rootPIDL != null)
{
rootPIDL = curr.rootPIDL;
}
else
{
data = curr.SerializeInt();
stack.Push(data);
}
curr = curr.ParentFolder;
}
if (rootPIDL == null && stack.Count == 0)
return IntPtr.Zero;
object[] x = stack.ToArray();
IntPtr[] pidls = null;
int count = stack.Count;
if (count > 0)
{
pidls = new IntPtr[stack.Count];
for (int i = 0; i < count; i++)
{
pidls[i] = (IntPtr)stack.Pop();
}
}
return CreatePIDL(rootPIDL, pidls);
}
My CreatePIDL implementation:
internal unsafe static IntPtr CreatePIDL(byte[] rootPIDL,IntPtr[] pidls)
{
int headerSize = Marshal.SizeOf(typeof(ushort));
int totalSize = headerSize;
if (rootPIDL != null)
totalSize += rootPIDL.Length - headerSize;
if (pidls!=null && pidls.Length > 0)
{
foreach (IntPtr data in pidls)
{
totalSize += PIDLSize(data);
}
}
IntPtr ret = PIDLAlloc(totalSize);
IntPtr currPos = ret;
if(rootPIDL!=null)
{
Marshal.Copy(rootPIDL, 0, currPos, rootLPIFQ.Length - headerSize);
currPos = Win32.AdvancePtr(currPos, rootLPIFQ.Length - headerSize);
}
if (pidls != null && pidls.Length>0)
{
foreach (IntPtr data in pidls)
{
int dataLength = PIDLSize(data);
Win32.CopyMemory(currPos, data, dataLength);
currPos = Win32.AdvancePtr(currPos, dataLength);
}
}
Marshal.WriteInt16(currPos, (short)0);
return ret;
}
internal static unsafe int PIDLSize(IntPtr ptr)
{
return (int) (*((ushort*)ptr));
}
internal unsafe static IntPtr PIDLAlloc(int size)
{
IntPtr ret = Marshal.AllocCoTaskMem(size);
if (ret == IntPtr.Zero)
throw new OutOfMemoryException();
return ret;
}

Answer 1

I found a workaround. It is not pretty nor optimal, yet it works well.
Instead of calling the notify with SHCNE_UPDATEDIR, I'm executing all three of the following notifiers in sequence:
Win32.SHChangeNotify(SHCNE_MKDIR, SHCNF_IDLIST | SHCNF_FLUSH, PIDL, IntPtr.Zero);
Win32.SHChangeNotify(SHCNE_CREATE, SHCNF_IDLIST | SHCNF_FLUSH, PIDL, IntPtr.Zero);
Win32.SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_IDLIST | SHCNF_FLUSH, PIDL, IntPtr.Zero);