Questions on UI for WinForms Forum

1 answer

14 views

[Solved] Can't set the SelectedValue programmatically when the value member is a string

I use a RadDropDownList, I want to give the user the ability to search the items in the drop down so I use the default DropDownStyle = DropDown with AutoCompleteMode = SuggestAppend.

However, I want to ensure that the user selects a valid item from the list and doesn't leave random text. So I created the extension method EnsureValidSelection() below that remembers the original value, and on validation resets it to that original value if no valid value is now selected.

This works well when the ValueMember is an int. But when it's a string, it ignores the code that sets the SelectedValue.

public static void EnsureValidSelection(this RadDropDownList combo)
{
    object originalValue = null;
    combo.Enter += DropDownEnter;
    combo.SelectedValueChanged += DropDownSelectedValueChanged;
    combo.Validated += DropDownValidated;
    return;

    void DropDownEnter(object sender, EventArgs e)
    {
        originalValue = ((RadDropDownList)sender).SelectedValue;
    }

    void DropDownSelectedValueChanged(object sender, EventArgs e)
    {
        if (originalValue != null && combo.SelectedValue != null)
            originalValue = combo.SelectedValue;
    }

    void DropDownValidated(object sender, EventArgs e)
    {
        if (combo.SelectedValue == null)
            combo.SelectedValue = originalValue;
        originalValue = null;
    }
}

DropDownList

answered on 24 Mar 2026

1 answer

24 views

Disabled text color remains gray instead of black in RadDropDownList / RadDateTimePicker (Telerik 2015 Q1, TSSP attached)

Hi, Telerik Team.

I’m using Telerik UI for WinForms 2015 Q1 with a custom theme, and I want the text color to remain black even when the control is disabled. Currently, when Enabled=False, the text automatically becomes gray.

My goal is for the text color to be black in both Enabled and Disabled states.

This already works for RadTextBox, using the HostedTextBoxBase approach from the forum.

However, for the following controls, the text still becomes gray when disabled:

RadDropDownList
RadDateTimePicker

I already modified the Disabled state in Visual Style Builder and updated elements like RadDropDownTextBoxElement and TextBoxFill(Fill Primitive). I’ve attached my .tssp file.

Could you please review the .tssp and let me know if there is any incorrect setting, or if I’m modifying the wrong element to keep the disabled text color black?

Also, if there is a recommended way to achieve this without using Visual Style Builder (for example programmatically), I would appreciate your guidance.

Thank you.

Calendar, DateTimePicker, TimePicker and Clock

DropDownList

answered on 25 Feb 2026

2 answers

113 views

GridView permanent filter editor. Size issues with RadDropDownListElement.

I've tried implement custom filter as per Permanent editor in a filter cell - Telerik UI for WinForms instruction
but when I run that project drop down list looks too small to hold its content. Please look at attached screenshot.

Could you advise me how to properly calculate size of dropdown, or in other way make it fit its content. The only way I found is to set

 this.dropDown.MinSize = new Size(150, 30);

inside CreateChildElements method. But I'm not sure this is the best way to fix this issue. Could you please advise me how to handle those kinds of size issues?

DropDownList

GridView

answered on 23 Jan 2025

1 answer

69 views

Item appears duplicated in the popup when selected Desert Theme

Hello,

How do i make the item appear only once in the popup when the theme is Desert?

1 - Without Theme

2 - Desert Theme

Code:

List<TecnicoServicoInfo> listaTecnicos = new List<TecnicoServicoInfo>();

TecnicoServicoInfo tec = new TecnicoServicoInfo();
tec.CdFuncionario = -1;
tec.DsFuncionario = " ";
TecnicoServicoInfo tec1 = new TecnicoServicoInfo();
tec1.CdFuncionario = 80;
tec1.DsFuncionario = "robsu";
TecnicoServicoInfo tec2 = new TecnicoServicoInfo();
tec2.CdFuncionario = 1558;
tec2.DsFuncionario = "joelssu";
TecnicoServicoInfo tec4 = new TecnicoServicoInfo();
tec4.CdFuncionario = 333;
tec4.DsFuncionario = "TESTE UM NOME MAIOR QUE TODOS OS OUTROS PARA VER O TEMA";
listaTecnicos.Add(tec);
listaTecnicos.Add(tec2);
listaTecnicos.Add(tec1);
listaTecnicos.Add(tec4);
listaTecnicos = listaTecnicos.OrderBy(x => x.DsFuncionario).ToList();

ddlTecnico.DropDownStyle = RadDropDownStyle.DropDown;
ddlTecnico.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
ddlTecnico.DropDownListElement.AutoCompleteSuggest.SuggestMode = SuggestMode.Contains;
ddlTecnico.Items.Clear();

ddlTecnico.DescriptionTextMember = "DsFuncionario";
ddlTecnico.ValueMember = "CdFuncionario";
ddlTecnico.DisplayMember = "DsFuncionario";

ddlTecnico.DataSource = listaTecnicos;

ddlproxima.DropDownStyle = RadDropDownStyle.DropDown;
ddlproxima.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
ddlproxima.DropDownListElement.AutoCompleteSuggest.SuggestMode = SuggestMode.Contains;
ddlproxima.Items.Clear();

ddlproxima.DescriptionTextMember = "DsFuncionario";
ddlproxima.ValueMember = "CdFuncionario";
ddlproxima.DisplayMember = "DsFuncionario";

ddlproxima.DataSource = listaTecnicos;

ddlproxima.AutoSizeItems = false;
ddlproxima.AutoSize = false;

Telerik version: 23.2.718

Thank You!

DropDownList

Themes and Visual Style Builder

answered on 03 Dec 2024

2 answers

96 views

DropDown Dynamic loadDate

I had a question about the Dropdown element, I saw how to search for it, but I couldn't find it for dynamic
    public SearchWarehouseNP()
    {
        InitializeComponent();
        dropdownSettlement.DropDownStyle = RadDropDownStyle.DropDown;
        dropdownSettlement.AutoCompleteMode = AutoCompleteMode.Suggest;

        dropdownSettlement.DropDownListElement.AutoCompleteSuggest = new CustomAutoCompleteSuggestHelperUpdate(
            dropdownSettlement.DropDownListElement,
            async query =>
            {
                if (string.IsNullOrWhiteSpace(query) || query.Length < 3)
                    return Enumerable.Empty<DescriptionTextListDataItem>();

                var response = await _searchSettlementService.GetCityData(query);
                if (response.success && response.data.Any())
                {
                    return response.data.First().Addresses.Select(a => new DescriptionTextListDataItem
                    {
                        Text = $"{a.MainDescription} ({a.Area})",
                        Value = a.MainDescription,
                        DescriptionText = a.Area
                    });
                }

                return Enumerable.Empty<DescriptionTextListDataItem>();
            }
        );

        dropdownSettlement.SelectedIndexChanged += (s, e) =>
        {
            if (dropdownSettlement.SelectedItem is DescriptionTextListDataItem selectedItem)
            {
                Console.WriteLine($"Выбрано: {selectedItem.Text} ({selectedItem.Value})");
            }
        };
    }
}
The problem is that the data is not stored in Items

Console.WriteLine empty


using Telerik.WinControls.UI;

namespace NovaPostOrderManager.Helpers;

public class CustomAutoCompleteSuggestHelperUpdate : AutoCompleteSuggestHelper
{
    private readonly Func<string, Task<IEnumerable<DescriptionTextListDataItem>>> _fetchDataAsync;
    private CancellationTokenSource _cts = new();

    public CustomAutoCompleteSuggestHelperUpdate(RadDropDownListElement owner, Func<string, Task<IEnumerable<DescriptionTextListDataItem>>> fetchDataAsync)
        : base(owner)
    {
        _fetchDataAsync = fetchDataAsync;
    }

    protected override async void SyncItemsCore()
    {
        // Текущий текст из поля ввода
        string currentInput = Filter;

        // Проверяем, нужно ли загружать данные
        if (string.IsNullOrWhiteSpace(currentInput) || currentInput.Length < 3)
        {
            DropDownList.ListElement.Items.Clear();
            DropDownList.ClosePopup();
            return;
        }

        // Отменяем предыдущий запрос
        _cts.Cancel();
        _cts = new CancellationTokenSource();

        try
        {
            // Задержка перед началом запроса
            await Task.Delay(300, _cts.Token);

            // Загружаем данные
            var items = await _fetchDataAsync(currentInput);

            _cts.Token.ThrowIfCancellationRequested();

            DropDownList.ListElement.BeginUpdate();
            DropDownList.ListElement.Items.Clear();

            // Добавляем элементы в выпадающий список
            foreach (var item in items)
            {
                DropDownList.ListElement.Items.Add(item);
            }

            DropDownList.ListElement.EndUpdate();

            if (DropDownList.ListElement.Items.Count > 0)
            {
                DropDownList.ShowPopup(); // Показываем список, если есть элементы
            }
            else
            {
                DropDownList.ClosePopup();
            }
        }
        catch (TaskCanceledException)
        {
            // Запрос был отменён — игнорируем
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Ошибка загрузки данных: {ex.Message}");
        }
    }

    protected override bool DefaultFilter(RadListDataItem item)
    {
        if (item is not DescriptionTextListDataItem descriptionItem)
            return base.DefaultFilter(item);

        return descriptionItem.Text.Contains(Filter, StringComparison.CurrentCultureIgnoreCase) ||
               descriptionItem.DescriptionText.Contains(Filter, StringComparison.CurrentCultureIgnoreCase);
    }
}

DropDownList

answered on 29 Nov 2024

1 answer

88 views

DropDownList in StatusStrip

Is there a simple way of making a simple DropDownList in the StatusStrip control? (or any other menu)

Thank you in advance.

DropDownList

StatusStrip

answered on 23 Oct 2024

1 answer

95 views

Remove down arrow in RadTabbedForm header

Hi,

how can I remove the arrow button in a RadTabbedForm header (WinForms)? Please see the attached photo

Thanks,

Roy

Buttons, RadioButton, CheckBox, etc

DropDownList

TabbedForm

answered on 23 Oct 2024

1 answer

168 views

[Solved] RadDropDownList disable arrow when readonly

Hello,

I am new to WinForms.

Is there a possibility to disable the Arrow for the RadDropDownList ?

When I set the component to readonly, I can still choose a new value via the arrow.

But then the value is never saved because it is read-only.

And wich property do I have to set for this?

DropDownList

answered on 18 Sep 2024

1 answer

123 views

RowsChanged is fired after CellEditorInitialized without any change

How to fix the issue below where a cell is marked with modified just because the cell was clicked?

Before the datasource is set.

After the datasource is set.

The value was not changed, but it is firing he RowsChanged.

How can avoid it to happen?

DropDownList

GridView

answered on 16 Sep 2024

1 answer

117 views

initialization radDropDownList after update a record in the table

Hi,

I have an RadDropDownList filled with some record of a table (ttSoc) using DataSource and bounded functionality.

I have a button that lets me add/delete records from this table (ttsoc).
Impossible to update the RadDropDownList

my code:

in the form load I run ChargeCodeSociete('InitBe').

In the click button I run ChargeCodeSociete('affiche').

METHOD PRIVATE VOID BtnSociete_Click( INPUT sender AS System.Object, INPUT e AS System.EventArgs ):

// On instancie la classe
oFrmSociete = NEW frmSociete().
// En attente du retour de la form en mode dialog box
WAIT-FOR oFrmSociete:ShowDialog().

oongDescriptionEtudeGeneral:ChargeCodeSociete('Affiche').

RETURN.

END METHOD.

IN oongDescriptionEtudeGenral FORM

METHOD PUBLIC VOID ChargeCodeSociete( INPUT ipcMode AS CHARACTER ):
CASE ipcMode:
WHEN 'InitBe' THEN DO:
beSociete= NEW fichier.description_etude.be.beSociete().

beSociete:ReadbeSociete(OUTPUT DATASET dsSoc).

//Associer le query du dataset au probadingSource
bsSociete:HANDLE = DATASET dsSoc:HANDLE.
END.
WHEN 'Affiche' THEN DO:
DATASET dsSoc:TOP-NAV-QUERY():QUERY-PREPARE("FOR EACH ttSoc").
DATASET dsSoc:TOP-NAV-QUERY():QUERY-OPEN().

DropDownListCodeSociete: ?????

END.
END CASE.

thank you for your feedback

DropDownList

answered on 26 Aug 2024