Opening multiple document windows with previous instance

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Diagnostics;
using System.IO;

namespace CodeProject.Sample
{
	/// <summary>
	/// Summary description for FrmTestHarness.
	/// </summary>
	public class FrmTestHarness : System.Windows.Forms.Form
	{
		private System.Windows.Forms.Label label1;
		private System.Windows.Forms.TextBox txtArgs;
		private System.Windows.Forms.Label label2;
		private System.Windows.Forms.TextBox txtExe;
		private System.Windows.Forms.Label lblRun;
		private System.Windows.Forms.Button btnRun;
		private System.Windows.Forms.Label label3;
		private System.Windows.Forms.Label label4;
		/// <summary>
		/// Required designer variable.
		/// </summary>
		private System.ComponentModel.Container components = null;

		public FrmTestHarness()
		{
			//
			// Required for Windows Form Designer support
			//
			InitializeComponent();

			//
			// TODO: Add any constructor code after InitializeComponent call
			//
		}

		/// <summary>
		/// Clean up any resources being used.
		/// </summary>
		protected override void Dispose( bool disposing )
		{
			if( disposing )
			{
				if(components != null)
				{
					components.Dispose();
				}
			}
			base.Dispose( disposing );
		}

		/// <summary>
		/// The main entry point for the application.
		/// </summary>
		[STAThread]
		static void Main() 
		{
			Application.Run(new FrmTestHarness());
		}

		#region Windows Form Designer generated code
		/// <summary>
		/// Required method for Designer support - do not modify
		/// the contents of this method with the code editor.
		/// </summary>
		private void InitializeComponent()
		{
			this.label1 = new System.Windows.Forms.Label();
			this.txtArgs = new System.Windows.Forms.TextBox();
			this.label2 = new System.Windows.Forms.Label();
			this.txtExe = new System.Windows.Forms.TextBox();
			this.lblRun = new System.Windows.Forms.Label();
			this.btnRun = new System.Windows.Forms.Button();
			this.label3 = new System.Windows.Forms.Label();
			this.label4 = new System.Windows.Forms.Label();
			this.SuspendLayout();
			// 
			// label1
			// 
			this.label1.Location = new System.Drawing.Point(24, 104);
			this.label1.Name = "label1";
			this.label1.Size = new System.Drawing.Size(160, 23);
			this.label1.TabIndex = 0;
			this.label1.Text = "Command Line Arguments:";
			this.label1.TextAlign = System.Drawing.ContentAlignment.BottomLeft;
			// 
			// txtArgs
			// 
			this.txtArgs.Anchor = ((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Left) 
				| System.Windows.Forms.AnchorStyles.Right);
			this.txtArgs.Location = new System.Drawing.Point(24, 128);
			this.txtArgs.Name = "txtArgs";
			this.txtArgs.Size = new System.Drawing.Size(352, 20);
			this.txtArgs.TabIndex = 1;
			this.txtArgs.Text = "FileName.ext";
			this.txtArgs.TextChanged += new System.EventHandler(this.txtArgs_TextChanged);
			// 
			// label2
			// 
			this.label2.Location = new System.Drawing.Point(24, 56);
			this.label2.Name = "label2";
			this.label2.Size = new System.Drawing.Size(160, 23);
			this.label2.TabIndex = 2;
			this.label2.Text = "Executable:";
			this.label2.TextAlign = System.Drawing.ContentAlignment.BottomLeft;
			// 
			// txtExe
			// 
			this.txtExe.Anchor = ((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Left) 
				| System.Windows.Forms.AnchorStyles.Right);
			this.txtExe.Location = new System.Drawing.Point(24, 80);
			this.txtExe.Name = "txtExe";
			this.txtExe.Size = new System.Drawing.Size(352, 20);
			this.txtExe.TabIndex = 3;
			this.txtExe.Text = "";
			this.txtExe.TextChanged += new System.EventHandler(this.txtExe_TextChanged);
			// 
			// lblRun
			// 
			this.lblRun.Anchor = ((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Left) 
				| System.Windows.Forms.AnchorStyles.Right);
			this.lblRun.Location = new System.Drawing.Point(32, 176);
			this.lblRun.Name = "lblRun";
			this.lblRun.Size = new System.Drawing.Size(344, 40);
			this.lblRun.TabIndex = 4;
			// 
			// btnRun
			// 
			this.btnRun.Anchor = System.Windows.Forms.AnchorStyles.Bottom;
			this.btnRun.Location = new System.Drawing.Point(156, 232);
			this.btnRun.Name = "btnRun";
			this.btnRun.Size = new System.Drawing.Size(72, 24);
			this.btnRun.TabIndex = 5;
			this.btnRun.Text = "Run";
			this.btnRun.Click += new System.EventHandler(this.btnRun_Click);
			// 
			// label3
			// 
			this.label3.Location = new System.Drawing.Point(24, 152);
			this.label3.Name = "label3";
			this.label3.Size = new System.Drawing.Size(160, 23);
			this.label3.TabIndex = 6;
			this.label3.Text = "Run Path:";
			this.label3.TextAlign = System.Drawing.ContentAlignment.BottomLeft;
			// 
			// label4
			// 
			this.label4.Location = new System.Drawing.Point(24, 16);
			this.label4.Name = "label4";
			this.label4.Size = new System.Drawing.Size(344, 32);
			this.label4.TabIndex = 7;
			this.label4.Text = "Make sure to copy SingleInstance.exe to same directory as this application.";
			this.label4.TextAlign = System.Drawing.ContentAlignment.BottomLeft;
			// 
			// FrmTestHarness
			// 
			this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
			this.ClientSize = new System.Drawing.Size(384, 270);
			this.Controls.AddRange(new System.Windows.Forms.Control[] {
																		  this.label4,
																		  this.label3,
																		  this.btnRun,
																		  this.lblRun,
																		  this.txtExe,
																		  this.label2,
																		  this.txtArgs,
																		  this.label1});
			this.Name = "FrmTestHarness";
			this.Text = "Single Instance Test Harness";
			this.Load += new System.EventHandler(this.FrmTestHarness_Load);
			this.ResumeLayout(false);

		}
		#endregion

		private void btnRun_Click(object sender, System.EventArgs e)
		{
			Process.Start( txtExe.Text, txtArgs.Text );
		}

		private void FrmTestHarness_Load(object sender, System.EventArgs e)
		{
			string path = Path.GetDirectoryName(Application.ExecutablePath);
			if ( path[path.Length - 1] != Path.DirectorySeparatorChar )
				path += Path.DirectorySeparatorChar;
			path += "SingleInstance.exe";
			if ( File.Exists( path ) )
				txtExe.Text = path;
		}

		private void txtExe_TextChanged(object sender, System.EventArgs e)
		{
			lblRun.Text = txtExe.Text + " \"" + txtArgs.Text + "\"";
		}

		private void txtArgs_TextChanged(object sender, System.EventArgs e)
		{
			lblRun.Text = txtExe.Text + " \"" + txtArgs.Text + "\"";
		}
	}
}