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Posted 31 Jul 2002


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ToolTipListBox - a list box with tool tips

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4.77/5 (16 votes)
31 Jul 20021 min read
A ListBox derived class that shows tool-tips for items that won't fit within the width of the list box


I was working on a project where I needed to have a list-box that would show tool tips for items that will not fit within the width of the list-box. Initially I thought there would be a .NET BCL class that would have this facility. I've had forgettable experiences in the past where I'd waste my time writing something that was already available. But this time I found nothing that met my requirements. So I wrote my own list box class derived from the .NET System.Windows.Forms.ListBox class and called it ToolTipListBox.

What it does

Whenever an item in the ToolTipListBox list-box exceeds the width of the list-box control, a tool-tip is floated just over the item. Tool-tips are floated only for items that won't fit within the width of the list-box. For items that do fit in, the tool-tip will not be shown.

Using it

Simply declare your list-box objects as members of the ToolTipListBox class instead of the standard ListBox class. That's all. You'll also have to include the ToolTipListBox class source file in your project. Or you might even build a library and reference it instead.

Class source listing

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

public class ToolTipListBox : System.Windows.Forms.ListBox
    public struct SIZE
        public int cx;
        public int cy;
    public static extern int GetTextExtentPoint32(IntPtr hdc, 
        String str, int len, ref SIZE size);

    public static extern IntPtr GetDC(IntPtr hWnd);

    public static extern int ReleaseDC(IntPtr hWnd,IntPtr hdc);

    public ToolTipListBox()
        tp.InitialDelay = 500;
        tp.ReshowDelay = 500;
        tp.AutoPopDelay = 3000;         
        tp.Active = true;           

    protected override void OnMouseMove(
        System.Windows.Forms.MouseEventArgs e)
        /* Get the index of the mouse-hovered item */
        int index = IndexFromPoint(e.X,e.Y);

        /* Ensure that there is an item */
        if(index != ListBox.NoMatches )
              Check if the mouse has moved enough
              distance for a new index 
            if( LastIndex != index )
                string s = Items[index].ToString(); 

                /* Get the text extent */
                IntPtr hdc = GetDC(this.Handle);
                SIZE size;
       = 0;
       = 0;
                GetTextExtentPoint32(hdc,s,s.Length,ref size);

                /* If it won't fit show tool-tip */
                if(this.Width <                    

                LastIndex = index;              

    private ToolTip tp = new ToolTip();
    private int LastIndex = -1;



This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

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About the Author

Nish Nishant
United States United States
Nish Nishant is a Principal Software Architect based out of Columbus, Ohio. He has over 17 years of software industry experience in various roles including Lead Software Architect, Principal Software Engineer, and Product Manager. Nish was a Microsoft Visual C++ MVP between 2002 and 2015.

Nish is an industry acknowledged expert in the Microsoft technology stack. He authored C++/CLI in Action for Manning Publications in 2005, and had previously co-authored Extending MFC Applications with the .NET Framework for Addison Wesley in 2003. In addition, he has over 140 published technology articles on and another 250+ blog articles on his WordPress blog. Nish is vastly experienced in team management, mentoring teams, and directing all stages of software development.

Contact Nish : If you are interested in hiring Nish as a consultant, you can reach him via his google email id voidnish.

Company Website :

Comments and Discussions

GeneralReally helped me out! Pin
Andrew Blackburn23-Dec-08 3:16
MemberAndrew Blackburn23-Dec-08 3:16 
GeneralMouse Click Over Tooltip Pin
Saied Javadi31-Aug-08 19:05
MemberSaied Javadi31-Aug-08 19:05 
QuestionTooltips for Combobox items ...???? Pin
Srivatsa Haridas16-Jan-08 19:52
professionalSrivatsa Haridas16-Jan-08 19:52 
GeneralToolTip overlay [modified] Pin
ZooZee1-May-07 0:39
MemberZooZee1-May-07 0:39 
GeneralRe: ToolTip overlay Pin
Marco Rosas8-Aug-07 6:40
MemberMarco Rosas8-Aug-07 6:40 
GeneralThank you Pin
rgeezy2-Nov-06 7:18
Memberrgeezy2-Nov-06 7:18 
GeneralRe: Thank you Pin
wlin7102051722-Nov-06 3:29
Memberwlin7102051722-Nov-06 3:29 
GeneralRe: Thank you Pin
wlin7102051722-Nov-06 3:42
Memberwlin7102051722-Nov-06 3:42 
GeneralRe: Thank you Pin
Anil_Atta25-Apr-07 7:54
MemberAnil_Atta25-Apr-07 7:54 
Questioncan this feature works in ASP??? Pin
rachellim9-Aug-06 17:00
Memberrachellim9-Aug-06 17:00 
GeneralGreat code Pin
Scarsymmetry18-Jul-06 0:17
MemberScarsymmetry18-Jul-06 0:17 
QuestionThis is not Supported on Framework 1.0 Pin
TanmaySN29-Nov-05 0:24
MemberTanmaySN29-Nov-05 0:24 
QuestionCan u do it For Pin
.NET Follower5-May-05 23:42
Member.NET Follower5-May-05 23:42 
AnswerRe: Can u do it For Pin
/randz5-Feb-07 19:31
Member/randz5-Feb-07 19:31 
QuestionNOT WORKING ??? Pin
De Nardis Andrea17-Feb-05 5:16
MemberDe Nardis Andrea17-Feb-05 5:16 
AnswerRe: NOT WORKING ??? Pin
De Nardis Andrea17-Feb-05 5:53
MemberDe Nardis Andrea17-Feb-05 5:53 
GeneralToolTip in a TreeView Control Pin
gsantanaz12-Jan-05 11:49
Membergsantanaz12-Jan-05 11:49 
GeneralToolTip on ComboBox Pin
Deena27-Nov-02 19:09
MemberDeena27-Nov-02 19:09 
GeneralRe: ToolTip on ComboBox Pin
Filipczako25-Aug-05 12:44
MemberFilipczako25-Aug-05 12:44 
GeneralNice :) Pin
leppie1-Aug-02 7:50
Memberleppie1-Aug-02 7:50 
QuestionWhat would be nice... Pin
Shog91-Aug-02 2:10
sitebuilderShog91-Aug-02 2:10 
AnswerRe: What would be nice... Pin
Nish Nishant1-Aug-02 6:05
sitebuilderNish Nishant1-Aug-02 6:05 
GeneralRe: What would be nice... Pin
Shog91-Aug-02 6:10
sitebuilderShog91-Aug-02 6:10 

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