Click here to Skip to main content
11,409,450 members (57,936 online)
Click here to Skip to main content

Read only ComboBox

, 11 Oct 2004
Rate this:
Please Sign up or sign in to vote.
How to make ComboBox read only


Surprisingly the MS Visual Studio ComboBox doesn’t have such an important property: ReadOnly. After searching on internet for solving this problem and not finding a relevant resolution I decided to add this important property to a new ComboBox control.

Using the code

Create a new derived class from ComboBox:

public class NewComboBox    : System.Windows.Forms.ComboBox

Declare private variables:

private bool readOnly;
private Color tBackColor;
private Color tForeColor;
private ContextMenu cmnuEmpty;
private ComboBoxStyle dropDownStyle = ComboBoxStyle.DropDown;
private Color readOnlyBackColor = SystemColors.Control;
private Color readOnlyForeColor = SystemColors.WindowText;

Set custom context menu to be display when read only:

public ReadOnlyComboBox()
  cmnuEmpty = new ContextMenu(); //code this menu for your needs

Declare ReadOnly property:

public bool ReadOnly
    return readOnly;
    if(readOnly != value)
      readOnly = value;
        this.ContextMenu = cmnuEmpty;
        base.DropDownStyle = ComboBoxStyle.Simple;
        base.Height = 21;
        this.tBackColor = this.BackColor;
        this.tForeColor = this.ForeColor;
        base.BackColor = this.ReadOnlyBackColor;
        base.ForeColor = this.ReadOnlyForeColor;
        this.ContextMenu = null;
        base.DropDownStyle = dropDownStyle;
        base.BackColor = tBackColor;
        base.ForeColor = tForeColor;

Override OnKeyDown and OnKeyPress events to stop editing when readonly:

protected override void OnKeyDown(KeyEventArgs e)  
  if(this.ReadOnly && (
    e.KeyCode == Keys.Up  || 
    e.KeyCode == Keys.Down  ||
    e.KeyCode == Keys.Delete))
    e.Handled = true;
    base.OnKeyDown (e);

protected override void OnKeyPress(KeyPressEventArgs e) 
        e.Handled = true;
        base.OnKeyPress (e);

Change the DropDownStyle property to reflect property changes only when not ReadOnly:

new public ComboBoxStyle DropDownStyle
    return dropDownStyle;
    if(dropDownStyle != value)
      dropDownStyle = value;
      if(!this.ReadOnly) base.DropDownStyle = value;

Add back/fore color properties to reflect changes in ReadOnly property:

public Color ReadOnlyBackColor
    return readOnlyBackColor;
    readOnlyBackColor = value;
public Color ReadOnlyForeColor
    return readOnlyForeColor;
    readOnlyForeColor = value;


Eliminate the white border that appears inside the client area when enable XP styles and BackColor is not default color.


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.

A list of licenses authors might use can be found here


About the Author

Software Developer (Senior)
Romania Romania
No Biography provided

Comments and Discussions

GeneralMust also disable mouse paste PinmemberFinishedOnTime26-Feb-07 4:25 
QuestionLatest code? PinmemberChuck_Esterbrook27-Dec-06 14:43 
GeneralKeyPress Event Handler Pinmemberjsteve1712-Dec-06 10:16 
GeneralVery good. Pinmemberjotaele31-Oct-06 0:00 
QuestionHow to remove the white border? Pinmembersick bastard1-Jan-06 22:59 
GeneralAnother approach for a ReadOnly ComboBox PinmemberClaudio Grazioli9-May-05 11:12 
GeneralRe: Another approach for a ReadOnly ComboBox PinmemberChuck_Esterbrook27-Dec-06 13:35 
GeneralToo bad.... Pinmemberemunews28-Feb-05 3:48 
After I saw this article, I thought there might be a much easier way to accomplish this goal: set the Enabled property to false and the fore and back colors to their appropriate read only colors.   If it worked, it would be really simple and the technique would work for any control.   Unfortunately, the ComboBox ignores the fore and back colors when the ComboBox is disabled.   Here's the code I tried:

      Private _readOnly As Boolean
      Private _savedEnabled As Boolean
      Private _savedBackColor As Color
      Private _savedForeColor As Color

      Public Property [ReadOnly]() As Boolean
                  Return _readOnly
            End Get
            Set(ByVal Value As Boolean)
                  'if the property value changed
                  If Value <> _readOnly Then
                        If Value Then
                              _savedEnabled = Me.Enabled
                              _savedBackColor = Me.BackColor
                              _savedForeColor = Me.ForeColor
                              Me.Enabled = False
                              Me.BackColor = SystemColors.Control
                              Me.ForeColor = SystemColors.WindowText
                              Me.Enabled = _savedEnabled
                              Me.BackColor = _savedBackColor
                              Me.ForeColor = _savedForeColor
                        End If
                        _readOnly = Value
                  End If
            End Set
      End Property

It's too bad this doesn't work.   I wonder if there's anyway to force the fore and back colors when the ComboBox is disabled.
GeneralReadOnlyComboBox in DropDownList Mode Pinmemberpgolds6-Dec-04 6:21 
GeneralRe: ReadOnlyComboBox in DropDownList Mode Pinmemberpgolds6-Dec-04 8:22 
GeneralRe: ReadOnlyComboBox in DropDownList Mode PinmemberDan Anatoli6-Dec-04 20:30 
GeneralRe: ReadOnlyComboBox in DropDownList Mode Pinmemberpgolds7-Dec-04 5:34 
GeneralOptional solution Pinmemberomacias20-Nov-04 9:43 
GeneralRe: Optional solution PinsussAnonymous21-Nov-04 1:02 
GeneralThank You. Pinmemberpgolds19-Nov-04 10:33 
GeneralRefreshing a DropDownList PinmemberPaco7612-Nov-04 8:31 
GeneralNice. One little remark. PinmemberBoyan Botev19-Oct-04 22:14 
GeneralRMB option cut enabled Pinmemberasela.gunawardena@ifs.lk5-Oct-04 1:03 
GeneralRe: RMB option cut enabled PinmemberDan Anatoli5-Oct-04 20:22 
GeneralRe: RMB option cut enabled PinmemberAsela Gunawardena25-Oct-04 0:56 
GeneralRe: Re: RMB option cut enabled PinmemberAsela Gunawardena25-Oct-04 0:58 
QuestionWhy not just change the DropDownStyle Property? PinsussAnonymous30-May-04 8:11 
AnswerRe: Why not just change the DropDownStyle Property? PinmemberDan Anatoli30-May-04 19:57 
GeneralDropDownList can open, but selection can't be changed. PinmemberHanan Nachmany25-Apr-04 2:35 
GeneralCombobox still recieves F4, PageDown and pageUp PinmemberGuemper17-Mar-04 21:11 
GeneralRe: Combobox still recieves F4, PageDown and pageUp PinmemberDan Anatoli18-Mar-04 19:23 
GeneralRe: Combobox still recieves F4, PageDown and pageUp Pinmemberedokan3-May-04 7:20 
General...and you can cut the text PinmemberMarcuse726-May-04 6:14 
GeneralRe: ...and you can cut the text PinmemberDan Anatoli31-May-04 0:02 
GeneralThat's the hard way... PinmemberRay Hayes12-Mar-04 5:02 
GeneralRe: That's the hard way... PinmemberDan Anatoli14-Mar-04 19:50 
GeneralThe easiest way.. Pinmemberyltsa25-Mar-05 22:28 
GeneralRe: That's the hard way... PinmemberSystem.Object21-Apr-06 10:29 
QuestionHOW to add this NewComboBox to the form? PinmemberNappo2310-Mar-04 9:21 
AnswerRe: HOW to add this NewComboBox to the form? PinmemberDan Anatoli10-Mar-04 20:48 
GeneralCombox the worst control PinmemberElNoNo10-Mar-04 4:44 
GeneralRe: Combox the worst control PinmemberRoger J10-Mar-04 4:52 
GeneralRe: Combox the worst control PinmemberSebCode11-Oct-04 4:44 
QuestionDropDownList? PinsitebuilderUwe Keim9-Mar-04 7:31 
AnswerRe: DropDownList? PinmemberDan Anatoli9-Mar-04 19:50 
GeneralRe: DropDownList? Pinmemberstringali6911-Mar-04 6:13 
GeneralRe: DropDownList? PinmemberDan Anatoli11-Mar-04 19:46 
GeneralRe: DropDownList? PinsussAnonymous15-Aug-04 22:09 
GeneralRe: DropDownList? PinmemberDan Anatoli16-Aug-04 1:52 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

| Advertise | Privacy | Terms of Use | Mobile
Web01 | 2.8.150414.5 | Last Updated 11 Oct 2004
Article Copyright 2004 by Dan.A.
Everything else Copyright © CodeProject, 1999-2015
Layout: fixed | fluid