hWnd error

[BarryM]

I was told that this piece coding to find the es_password state in c# would work but an error message saying hWnd does not exist in the current context

  internal static class UnsafeNativeMethods 
        {
            public const int GWL_STYLE = -16;
            public const int ES_PASSWORD = 0x20;
            [DllImport("user32.dll")]
            public static extern int GetClassName(HandleRef hWnd, System.Text.StringBuilder lpClassName, int nMaxCount);
            [DllImport("user32.dll", EntryPoint = "GetWindowLong", CharSet = CharSet.Auto)]
            public static extern IntPtr GetWindowLong32(System.Runtime.InteropServices.HandleRef hWnd, int nIndex);
        
       }
        
      
        private void tmrpass_Tick(object sender, EventArgs e)
        {

            //start timer and espassword code

            // root the handle so it doesn't get disposed until were done with it

            Object root = new Object();

            System.Runtime.InteropServices.HandleRef handleRef = new System.Runtime.InteropServices.HandleRef(root, hWnd);
            System.Text.StringBuilder sb = new System.Text.StringBuilder(1024);
            // get the class name of the window
            UnsafeNativeMethods.GetClassName(new System.Runtime.InteropServices.HandleRef(root, hWnd), sb, sb.Capacity);
            // is it an edit box?
            if (sb.ToString() == "Edit" || sb.ToString().StartsWith("WindowsForms10.EDIT.app"))
            {
                // get the window style of the edit box
                int style = UnsafeNativeMethods.GetWindowLong32(new System.Runtime.InteropServices.HandleRef(root, hWnd), UnsafeNativeMethods.GWL_STYLE).ToInt32();
                // is it a password edit or not?
                if ((style & UnsafeNativeMethods.ES_PASSWORD) == UnsafeNativeMethods.ES_PASSWORD)
                {
                    lblkd.Text = "edit is password text box";
                }
                else
                {
                    lblkd.Text = "edit is not password text box";
                }
            }

            //stop timer and es password code
        }

i had fixed up all these other errors but not this one.
if you have any slight of an idea please reply thanks