public static class DisplayFusionFunction
{
    public static void Run(IntPtr windowHandle)
    {
        if (BFS.Input.IsKeyDown("16")) // Run only, if the Shift key is pressed during start of this function
        {
                BFS.Dialog.ShowMessageInfo(BFS.Window.GetText(windowHandle));
        }
    }
}

using System;
using System.Threading.Tasks;
using System.Net;

public static class DisplayFusionFunction
{
    public static void Run(IntPtr windowHandle)
    {
        ExplorerWindows.InitExplorerHandler();
        BFS.Dialog.ShowMessageInfo(ExplorerWindows.GetPath(windowHandle));
      }
}

// The following code is adapted from this solution:
// https://stackoverflow.com/questions/36886355/retrieve-the-full-path-of-an-explorer-window-through-a-handle-in-c-sharp
public static class ExplorerWindows
{
    static Guid CLSID_ShellApplication = new Guid("13709620-C279-11CE-A49E-444553540000");
    static Type shellApplicationType = Type.GetTypeFromCLSID(CLSID_ShellApplication, true);
    static object shellApplication = null;
    static object windows = null;
    static Type windowsType = null;
    static object count = null;
    
    public static void InitExplorerHandler()
    {
        shellApplication = Activator.CreateInstance(shellApplicationType);
        windows = shellApplicationType.InvokeMember("Windows", System.Reflection.BindingFlags.InvokeMethod, null, shellApplication, new object[] { });        
        windowsType = windows.GetType();
        count = windowsType.InvokeMember("Count", System.Reflection.BindingFlags.GetProperty, null, windows, null);
    }
    
    public static string GetPath(IntPtr windowHandle)
    {
        string currDirectory = "";
        Parallel.For(0, (int)count, i =>
        {
            try
            {
                object item = windowsType.InvokeMember("Item", System.Reflection.BindingFlags.InvokeMethod, null, windows, new object[] { i });
                Type itemType = item.GetType();
                string itemName = (string)itemType.InvokeMember("Name", System.Reflection.BindingFlags.GetProperty, null, item, null);
                if (itemName == "Windows Explorer" || itemName == "File Explorer" || itemName == "Explorer")
                {
                    string itemHandle = itemType.InvokeMember("HWND", System.Reflection.BindingFlags.GetProperty, null, item, null).ToString();
                    if (itemHandle == windowHandle.ToString())
                    {
                        currDirectory = (string)itemType.InvokeMember("LocationURL", System.Reflection.BindingFlags.GetProperty, null, item, null);
                    }
                }
            }
            catch (Exception e)
            {

            }
        });
        
        return WebUtility.HtmlDecode(currDirectory);
    }
}