Added C#-WinForms implementation of timer example

C#-WinForms/timer/README.md

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+To compile under Windows run:
+csc.exe /target:winexe timer.cs

C#-WinForms/timer/timer.cs

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+using System;
+using System.Drawing;
+using System.Windows.Forms;
+
+namespace Timer
+{
+    static class Program
+    {
+        [STAThread]
+        static void Main()
+        {
+            Application.EnableVisualStyles();
+            Application.SetCompatibleTextRenderingDefault(false);
+
+            int duration = 25;
+            decimal elapsedTime = 0;
+
+            var labelElapsedText = new Label();
+            labelElapsedText.Location = new Point(12, 22);
+            labelElapsedText.Text = "Elapsed Time:";
+            labelElapsedText.AutoSize = true;
+
+            var progressBar = new ProgressBar();
+            progressBar.Bounds = new Rectangle(92, 12, 180, 23);
+
+            var labelElapsedValue = new Label();
+            labelElapsedValue.Location = new Point(12, 51);
+            labelElapsedValue.Text = "00.0s";
+            labelElapsedValue.AutoSize = true;
+
+            var labelDuration = new Label();
+            labelDuration.Location = new Point(12, 80);
+            labelDuration.Text = "Duration:";
+            labelDuration.AutoSize = true;
+
+            var trackBar = new TrackBar();
+            trackBar.Bounds = new Rectangle(92, 70, 180, 45);
+            trackBar.TickStyle = TickStyle.None;
+            trackBar.Maximum = 50;
+            trackBar.Value = duration;
+
+            var button = new Button();
+            button.Bounds = new Rectangle(15, 121, 257, 23);
+            button.Text = "Reset";
+
+            var timer = new System.Windows.Forms.Timer();
+
+            button.Click += delegate { elapsedTime = 0; };
+            trackBar.Scroll += delegate { duration = trackBar.Value; };
+
+            timer.Tick += delegate
+            {
+                if (elapsedTime == duration)
+                {
+                    return;
+                }
+
+                if (elapsedTime > duration)
+                {
+                    elapsedTime = duration;
+                }
+                else
+                {
+                    elapsedTime += 0.1M;
+                }
+
+                labelElapsedValue.Text = elapsedTime.ToString("00.0") + "s";
+
+                if (duration == 0)
+                {
+                    progressBar.Value = 100;
+                }
+                else
+                {
+                    progressBar.Value = (int)(elapsedTime * 100 / duration);
+                }
+            };
+
+            timer.Start();
+
+            var form = new Form();
+            form.ClientSize = new Size(287, 155);
+            form.Text = "Timer";
+            form.Controls.Add(labelElapsedText);
+            form.Controls.Add(progressBar);
+            form.Controls.Add(labelElapsedValue);
+            form.Controls.Add(labelDuration);
+            form.Controls.Add(trackBar);
+            form.Controls.Add(button);
+
+            Application.Run(form);
+        }
+    }
+}