UnsettableComboBox.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / fx / src / Designer / WebForms / System / Web / UI / Design / Util / UnsettableComboBox.cs / 1 / UnsettableComboBox.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

// UnsettableComboBox.cs 
// 
// 12/22/98: Created: [....]
// 

namespace System.Web.UI.Design.Util {

    using System; 
    using System.Design;
    using System.ComponentModel; 
    using System.Windows.Forms; 
    using System.Diagnostics;
    using System.Drawing; 
    using System.Web.UI.Design;

    /// 
    ///  
    ///   Standard combobox with a "Not Set" item as the first item in its dropdown.
    ///   It also automatically blanks out the "Not Set" item on losing focus. 
    ///  
    /// 
    [System.Security.Permissions.SecurityPermission(System.Security.Permissions.SecurityAction.Demand, Flags=System.Security.Permissions.SecurityPermissionFlag.UnmanagedCode)] 
    internal sealed class UnsettableComboBox : ComboBox {
        private string notSetText;
        private bool internalChange;
 
        public UnsettableComboBox() {
            notSetText = SR.GetString(SR.UnsettableComboBox_NotSet); 
            Items.Add(notSetText); 
        }
 
        public string NotSetText {
            get {
                return notSetText;
            } 
            set {
                notSetText = value; 
                Items.RemoveAt(0); 
                Items.Insert(0, notSetText);
            } 
        }

        public override string Text {
            get { 
                if ((this.SelectedIndex == 0) || (this.SelectedIndex == -1))
                    return String.Empty; 
                else 
                    return base.Text;
            } 
            set {
                base.Text = value;
            }
        } 

        public void AddItem(object item) { 
            Items.Add(item); 
        }
 
        public void EnsureNotSetItem() {
            if (Items.Count == 0) {
                Items.Add(notSetText);
            } 
        }
 
        public bool IsSet() { 
            return SelectedIndex > 0;
        } 

        protected override void OnLostFocus(EventArgs e) {
            base.OnLostFocus(e);
 
            if (SelectedIndex == 0) {
                internalChange = true; 
                SelectedIndex = -1; 
                internalChange = false;
            } 
        }

        protected override void OnSelectedIndexChanged(EventArgs e) {
            if (internalChange == false) { 
                base.OnSelectedIndexChanged(e);
            } 
        } 
    }
} 


// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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