如何使用c#获取当前活动窗口的标题？

using System.Windows.Forms;

public class clsWindowInfo
{
    public string windowTitle { get; set; }
    public clsWindowInfo(IntPtr hwnd)
    {
        Win32.GetWindowText(hwnd, out windowTitle);
    }
}

public static void Main()
{
    Win32.POINT lpPoint = new Win32.POINT();
    Win32.GetCursorPos(out lpPoint);
    IntPtr hWnd = Win32.WindowFromPoint(lpPoint);
    Win32.GetClassName(hWnd, out Win32.clsWindowInfo info);
    windowTitle = info.windowTitle;
}

public static class Win32
{
    static Win32()
    {
        WNDCLASSEX wcex = new WNDCLASSEX();
        // ... 添加 WNDCLASSEX 成员变量。
    }

    [DllImport("user32.dll")]
    public static extern IntPtr GetWindowText(IntPtr hWnd, StringBuilder lpBuffer, int nMaxCount);

    [DllImport("user32.dll")]
    public static extern bool GetClassName(IntPtr hWnd, StringBuilder lpClassName, int nMaxCount);

    [StructLayout(LayoutKind.Sequential)]
    public struct RECT
    {
        public int Left;
        public int Top;
        public int Right;
        public int Bottom;
    }
    public struct POINT
    {
        public int X;
        public int Y;
    }
}