WPF ComboBox with custom dropdown width

问题

How can I extend width of dropdown of a combo, like Run dialog:

回答1:

Popup is a part of ComboBox template ("PART_Popup"). Add a Style for Popup to combobox Resources and set appropriate width there.

<ComboBox>
    <ComboBox.Resources>
        <Style TargetType="Popup">
            <Setter Property="Width" Value="1000"/>
        </Style>
    </ComboBox.Resources>
</ComboBox>

note also that there is a binding for Popup.MinWidth in template so you can't make it too small.

来源：https://stackoverflow.com/questions/43246876/wpf-combobox-with-custom-dropdown-width