C# WPF Combobox dropdown list to multiple columns

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>

Answer 2

Well, you can, here's the XAML:

<ComboBox Name="ComboBox">
    <ComboBox.ItemsPanel>
        <ItemsPanelTemplate>
            <UniformGrid Columns="2"/>
        </ItemsPanelTemplate>
    </ComboBox.ItemsPanel>
</ComboBox>

Now a simple test, adding numbers from 0 to 8 gives:

Now you can style it all you want... :)

Of course every item (every number, in this particular case) is separate, clickable item, just so there are no misunderstandings.

[EDIT] I have just noticed you want to do it 'the opposite way', that is in 'rows' direction, if so, then maybe it's better to use the WrapPanel instead, as someone suggested in the other answer. The UniformGrid fills the grid in the column-wise direction first.

Maybe there's a way to do it with UniformGrid, but there's no apparent and easy one-click change (I was wrong here before :) )