public static WindowRectangle CheckWindow(int height, int width)
        {
            // Have to declare a delegate so that a thunk is created, so that win32 may call us back.
            EnumWindowsCallback callBackFn = new EnumWindowsCallback(ReportWindow);

            heightWindow = height;
            widthWindow  = width;
            EnumWindows(callBackFn, 0);
            WindowRectangle w = new WindowRectangle();

            w.Left   = rectangleOfWindow.Left;
            w.Right  = rectangleOfWindow.Right;
            w.Top    = rectangleOfWindow.Top;
            w.Bottom = rectangleOfWindow.Bottom;
            return(w);
        }
        public void timer_Tick(object sender, EventArgs e)
        {
            //get coordinates of textview
            if (wr.Equals(null) || wr.Left == 0)
            {
                wr = WindowEnumerator.CheckWindow((int)textView.ViewportHeight, (int)textView.ViewportWidth);
                return;
            }

            if (eyePoint.X < wr.Left || eyePoint.Y < wr.Top || eyePoint.Y > wr.Bottom || eyePoint.X > wr.Right)
            {
                //outside of textview, so return, no update.
                return;
            }
            else
            {
                int startPosition = textView.TextSnapshot.GetLineNumberFromPosition(textView.TextViewLines.FirstVisibleLine.Start);
                int endPosition   = textView.TextSnapshot.GetLineNumberFromPosition(textView.TextViewLines.LastVisibleLine.Start);

                int    noOfLines  = endPosition - startPosition;
                double noOfPixels = noOfLines * textView.LineHeight;
                double lineNumberRelativeToView = (eyePoint.Y - wr.Top) / (textView.LineHeight * (textView.ZoomLevel / 100));
                double lineNumberAbsoluteToView = lineNumberRelativeToView + (startPosition);

                lineNumber = Math.Ceiling(lineNumberAbsoluteToView);

                try
                {
                    currentLineCounter[(int)lineNumber - 1]++;
                }
                catch (IndexOutOfRangeException)
                {
                    currentLineCounter[currentLineCounter.Length - 1]++;
                }

                Debug.WriteLine("Gazing at line: " + lineNumber);
            }
        }