Winforms -- multi select dropdown list

There is yet another fix:

The above solution is correct to fix the first issue, where it required two clicks to enter the list of checkboxes, however, this introduces a new issue when you click the control to exit it, it retains focus and you must double click to go to another control. I was able to fix this with the following code:

In CheckBoxComboBox.cs add the following override:

    protected override void OnClick(EventArgs e)
    {
        base.OnClick(e);
        this.Parent.Focus();
    }

With the answer from Rob P. and this answer, it will not hold focus on either click event.

Check out this project on CodeProject:

• CheckBox ComboBox Extending the ComboBox Class and Its Items