Task Dialog - Is it possible to add a Combo Box or a MultiColumnComboBox to a Task Dialog?

Hi Bonnie,

I can suggest you two ways to have no item selected in the RadDropDownList. The first way is to use the CurrentForm property in the RadTaskDialog which gets the current RadTaskDialogForm holding the dialog and you can subscribe for the Shown event , where you set the selected index to -1.

private void CurrentForm_Shown(object sender, EventArgs e)
{
    dropdownButton.SelectedIndex = -1;
}

The second approach is to use the SelectedIndexChanging event in the RadDropDownList which fires before SelectedIndex is changed and the event allows the operation to be canceled. 

bool isLoading = true;
private void DropdownButton_SelectedIndexChanging(object sender, Telerik.WinControls.UI.Data.PositionChangingCancelEventArgs e)
{
    if (isLoading)
    {
        e.Cancel = true;
        isLoading = false;
    }
}

Here are the links to the documentation  as well, where you can see more information about the events and properties which you can use:

https://docs.telerik.com/devtools/winforms/controls/dropdown-listcontrol-and-checkeddropdownlist/dropdownlist/properties-methods-events

https://docs.telerik.com/devtools/winforms/controls/task-dialog/task-dialog-properties-methods-events

I am sending you the example project as well. 

Hope this helps you.

Regards,
Maria
Progress Telerik

Hi Bonnie,

The RadTaskDialog control supports different element types that can be added to a RadTaskDialogPage which represents the main container that hosts the elements. It is possible to add different elements like RadDropDownList(ComboBox) to the TaskDialog. I am sending you a sample project, where I have added RadButtonElement and RadDropDownListElement into the RadioButtons collection and a link to the documentation as well.

https://docs.telerik.com/devtools/winforms/controls/task-dialog/task-dialog-element-types

I hope this helps you, if this is not what you want don't hesitate to write again.

Regards,
Maria
Progress Telerik