Enumerate open windows

OpenWindowGetter.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AVSPEED.Helper
{
    using System.Runtime.InteropServices;
    using HWND = IntPtr;
    /// <summary>Contains a method to get all the open windows.</summary>

    public static class OpenWindowGetter
    {
        /// <summary>Returns a dictionary that contains the handle and title of all the open windows.</summary> /// <returns>A dictionary that contains the handle and title of all the open windows.</returns>

        public static IDictionary<HWND, string> GetOpenWindows()
        {
            HWND lShellWindow = GetShellWindow();
            Dictionary<HWND, string> lWindows = new Dictionary<HWND, string>();

            EnumWindows(delegate (HWND hWnd, int lParam)
            {
                if (hWnd == lShellWindow) return true;
                if (!IsWindowVisible(hWnd)) return true;

                int lLength = GetWindowTextLength(hWnd);
                if (lLength == 0) return true;

                StringBuilder lBuilder = new StringBuilder(lLength);
                GetWindowText(hWnd, lBuilder, lLength + 1);

                lWindows[hWnd] = lBuilder.ToString();
                return true;

            }, 0);

            return lWindows;
        }

        delegate bool EnumWindowsProc(HWND hWnd, int lParam);

        [DllImport("USER32.DLL")]
        static extern bool EnumWindows(EnumWindowsProc enumFunc, int lParam);

        [DllImport("USER32.DLL")]
        static extern int GetWindowText(HWND hWnd, StringBuilder lpString, int nMaxCount);

        [DllImport("USER32.DLL")]
        static extern int GetWindowTextLength(HWND hWnd);

        [DllImport("USER32.DLL")]
        static extern bool IsWindowVisible(HWND hWnd);

        [DllImport("USER32.DLL")]
        static extern IntPtr GetShellWindow();
    }
}