Question

Is it possible to “force” the combobox items in list to appear in say two columns?

For example like this:

CB Selected Item

CB Item 1 | CB Item 4

CB Item 2 | CB Item 5

CB Item 3 |

Answer 1

You can change the ItemsPanel to a WrapPanel, just be careful on the height (you could write a converter to calculate it according to the number of items) :

<ComboBox>
    <ComboBox.Resources>
        <Style TargetType="ComboBox">
            <Setter Property="ItemsPanel">
                <Setter.Value>
                    <ItemsPanelTemplate>
                        <WrapPanel IsItemsHost="True" Orientation="Vertical" Width="100" Height="50" />
                    </ItemsPanelTemplate>
                </Setter.Value>
            </Setter>
        </Style>
        <Style TargetType="ComboBoxItem">
            <Setter Property="Width" Value="50" />
        </Style>
    </ComboBox.Resources>

    <ComboBoxItem Content="Value 1" />
    <ComboBoxItem Content="Value 2" />
    <ComboBoxItem Content="Value 3" />
    <ComboBoxItem Content="Value 4" />
    <ComboBoxItem Content="Value 5" />
</ComboBox>