If you're looking for a programmatic way to get a screenshot of the main window of a given process, here is a function that does it:

    public static Bitmap TakeScreenshot(Process process)
    {
        // may need a process Refresh before
        return TakeScreenshot(process.MainWindowHandle);
    }

    public static Bitmap TakeScreenshot(IntPtr handle)
    {
        RECT rc = new RECT();
        GetWindowRect(handle, ref rc);
        Bitmap bitmap = new Bitmap(rc.right - rc.left, rc.bottom - rc.top);
        using (Graphics graphics = Graphics.FromImage(bitmap))
        {
            PrintWindow(handle, graphics.GetHdc(), 0);
        }
        return bitmap;
    }

    [DllImport("user32.dll")]
    private static extern bool GetWindowRect(IntPtr hWnd, ref RECT rect);

    [DllImport("user32.dll")]
    private static extern bool PrintWindow(IntPtr hWnd, IntPtr hDC, int flags);

    [StructLayout(LayoutKind.Sequential)]
    private struct RECT
    {
        public int left;
        public int top;
        public int right;
        public int bottom;
    }

Unfortunately, on Aero-equipped OS (Vista/Win7/Win8) it will not capture the full transparent border. The usual transparent border will be blacked instead. Maybe it's enough for what you're trying to acomplish.