C#

System.Windows.Forms.ListBox.SelectedIndexCollection indices  = this.listBox1.SelectedIndices;

if (indices.Contains(0) && indices.Contains(3) && indices.Contains(6))
    //are selected

bool CheckIsSelected(int[] desiredIndices)
{
    System.Windows.Forms.ListBox.SelectedIndexCollection indices = this.listBox1.SelectedIndices;

    bool selected = true;

    foreach (int index in desiredIndices)
        if (!indices.Contains(index))
        {
            selected = false;
            break;
        }

    if (selected) return true;
    return false;
}

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

namespace ListBoxTest
{
	/// <summary>
	/// Summary description for Form1.
	/// </summary>
	public class Form1 : System.Windows.Forms.Form
	{
		private System.Windows.Forms.ListBox listBox1;
		private System.Windows.Forms.Button button1;
		/// <summary>
		/// Required designer variable.
		/// </summary>
		private System.ComponentModel.Container components = null;

		public Form1()
		{
			//
			// 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 );
		}

		#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.listBox1 = new System.Windows.Forms.ListBox();
			this.button1 = new System.Windows.Forms.Button();
			this.SuspendLayout();
			// 
			// listBox1
			// 
			this.listBox1.Items.AddRange(new object[] {
														  "1",
														  "2",
														  "3",
														  "4",
														  "5",
														  "6",
														  "7"});
			this.listBox1.Location = new System.Drawing.Point(144, 24);
			this.listBox1.Name = "listBox1";
			this.listBox1.SelectionMode = System.Windows.Forms.SelectionMode.MultiExtended;
			this.listBox1.Size = new System.Drawing.Size(352, 225);
			this.listBox1.TabIndex = 0;
			this.listBox1.SelectedIndexChanged += new System.EventHandler(this.listBox1_SelectedIndexChanged);
			// 
			// button1
			// 
			this.button1.Location = new System.Drawing.Point(144, 272);
			this.button1.Name = "button1";
			this.button1.Size = new System.Drawing.Size(352, 24);
			this.button1.TabIndex = 1;
			this.button1.Text = "button1";
			this.button1.Click += new System.EventHandler(this.button1_Click);
			// 
			// Form1
			// 
			this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
			this.ClientSize = new System.Drawing.Size(632, 446);
			this.Controls.Add(this.button1);
			this.Controls.Add(this.listBox1);
			this.Name = "Form1";
			this.Text = "Form1";
			this.ResumeLayout(false);

		}
		#endregion

		/// <summary>
		/// The main entry point for the application.
		/// </summary>
		[STAThread]
		static void Main() 
		{
			Application.Run(new Form1());
		}

		private void listBox1_SelectedIndexChanged(object sender, System.EventArgs e)
		{
		
		}

		private void button1_Click(object sender, System.EventArgs e)
		{
			int[] desiredIndices = new int[] { 0, 3, 6 };

			MessageBox.Show(CheckIsSelected(desiredIndices).ToString());
		}

		bool CheckIsSelected(int[] desiredIndices)
		{
			System.Windows.Forms.ListBox.SelectedIndexCollection indices = this.listBox1.SelectedIndices;

			bool selected = true;

			foreach (int index in desiredIndices)
				if (!indices.Contains(index))
				{
					selected = false;
					break;
				}

			if (selected) return true;
			return false;
		}
	}
}

Giorgi Dalakishvili wrote:

How can a file be in use if you are creating it?

Giorgi Dalakishvili wrote:

How can a file be in use if you are creating it?

using System;
using System.ComponentModel;
 
namespace YourNamespace
{
	public class ReadOnlyCheckBox : System.Windows.Forms.CheckBox
	{
		/// <summary>
		/// constructor (empty)
		/// </summary>
		public ReadOnlyCheckBox()
		{
		}
 
		private bool _readonly = true;
 
		/// <summary>
		/// This property enables/disables the functonality of the control
		/// </summary>
		[Category("ReadOnlySpecials")]
		[Description("This property enables/disables the functonality of the control")]
		[DefaultValue(true)]
		public bool ReadOnly
		{
			get
			{
				return _readonly;
			}
			set
			{
				if(value!=_readonly)
				{
					_readonly = value;
				}
			}
		}
 
		protected override void OnMouseDown(System.Windows.Forms.MouseEventArgs e)
		{
			//base method is only called,if ReadOnly is "false"
			if(!ReadOnly)
				base.OnMouseDown (e);
		}
	}
}

protected override void OnKeyPress(System.Windows.Forms.KeyPressEventArgs e)
{
    if(ReadOnly)
    {
        e.Handled = true;
    }
    base.OnKeyPress (e);
}