Often I Prefer single instance application on Form

    internal static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>


        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool SetForegroundWindow(IntPtr hWind);

        [DllImport("user32.dll")]
        private static extern bool ShowWindowAsync(IntPtr hWind, int cmd);


        [STAThread]
        private static void Main()
        {
            bool mutexWasCreated;
            var mut = new Mutex(true, "{..arun@darkside..}", out mutexWasCreated);
            if (mutexWasCreated)
            {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new Form1());
                mut.ReleaseMutex();
            }
            else
            {
                Process current = Process.GetCurrentProcess();
                for (int index = 0; index < Process.GetProcessesByName(current.ProcessName).Length; index++)
                {
                    Process process = Process.GetProcessesByName(current.ProcessName)[index];
                    if (process.Id == current.Id) continue;
                    SetForegroundWindow(process.MainWindowHandle);
                    ShowWindowAsync(process.MainWindowHandle, 9);
                    break;
                }
            }
        }
    }

often I Like to Scroll at Bottom

Autoscroll (TextBox, ListBox, ListView) [C#]

This example demonstrates how to programatically autoscroll WinForm controls TextBox, ListBox, ListView, TreeView and DataGridView.
Autoscroll to the end of box or view is useful, for example, in situations when you use one of these components as the output log window. Usually you add the items to the box or view and you want to be sure that the last added item is visible without the necessary to do it manually.
Though it's not difficult to solve this problem, .NET doesn't provide any unified way how to do it.

TextBox autoscroll

[C#]

textBox1.SelectionStart = textBox1.Text.Length;
textBox1.ScrollToCaret();

ListBox autoscroll

[C#]

listBox1.SelectedIndex = listBox1.Items.Count - 1;
listBox1.SelectedIndex = -1;

ListView autoscroll

[C#]

listView1.EnsureVisible(listView1.Items.Count - 1);

TreeView autoscroll

[C#]

treeView1.Nodes[treeView1.Nodes.Count - 1].EnsureVisible();

DataGridView autoscroll

[C#]

dataGridView1.FirstDisplayedCell =
  dataGridView1.Rows[dataGridView1.Rows.Count - 1].Cells[0]; 

Found at http://www.csharp-examples.net/autoscroll/

Hide Show Panel at RunTime

 if (hideToolStripMenuItem.Text != @"Hide")
            {
                if (hideToolStripMenuItem.Text != @"Show") return;
                splitContainer1.Panel2.Visible = true;
                splitContainer1.Panel2Collapsed = false;
                hideToolStripMenuItem.Text = @"Hide";
                return;
            }
            splitContainer1.Panel2.Visible = false;
            splitContainer1.Panel2Collapsed = true;
            hideToolStripMenuItem.Text = @"Show";

Pdf embedded Resource displaying at Run Time

                Stream sr = Assembly.GetExecutingAssembly().GetManifestResourceStream("P2PC.ppc.pdf");
                if (sr == null) return;
                var reader = new BufferedStream(sr);
                tempfile = Path.GetTempFileName() + ".pdf";
                var data = new byte[reader.Length];
                reader.Read(data, 0, (int) reader.Length);
                File.WriteAllBytes(tempfile, data);
                axAcroPDF1.Visible = true;
                axAcroPDF1.LoadFile(tempfile);

to delete...

axAcroPDF1.Visible = false;
            if (tempfile != null) File.Delete(tempfile);

Cross Thread Exception in Same thread in WinForm Controls

recently i came across problem over rich text box control,on updating string 

richTextBox1.Text += "Client Started" + Environment.NewLine;

Is replaced by

Invoke(new Action(() => richTextBox1.Text += "Client Started" + Environment.NewLine));

Note: if You're using .net 2.0runtime build declare 
public delegate void Action();//do not return the value
write it outside of a class.