class Program
{
    static void Main(string[] args)
    {
        int WS_EX_TOPMOST = 0x00000008;
        int GWL_EXSTYLE = -20;
        foreach (Process proc in Process.GetProcesses())
        {
            IntPtr hWnd = proc.MainWindowHandle;
            int res = GetWindowLong(hWnd, GWL_EXSTYLE);
            if ((res & WS_EX_TOPMOST) == WS_EX_TOPMOST)
            {
                Console.WriteLine("Topmost window found for process " + proc.ProcessName);
            }
        }
    }

    [DllImport("user32.dll")]
    static extern int GetWindowLong(IntPtr hWnd, int nIndex);
}