Question

In my comboBoxes that have many items (> 10), I need to either:
(a) Have all of the items display when the dropdown occurs
-or:
(b) Reduce the space between the items (it seems excessive, almost “cartoonish”)

So, I would really prefer both. How can I do one or the other or both?

It would seem the MaxDropDownHeight property would be just the ticket, but set to Infinity it doesn’t work/has a strange definition of Infinity.

Here’s the XAML for one of them with this problem:

<ComboBox x:Name="comboBoxDay" Grid.Row="4" Grid.Column="5" Margin="8" IsEnabled="False"></ComboBox>

…and what it contains:

for (int i = 1; i < 32; i++)
{
    comboBoxDay.Items.Add(i);
}

UPDATE

Setting the height to 15 cuts off part of the text; so does 18. And even then, only March-November are displayed. I also set MaxDropDownHeight to first 320, then 520. Here’s the entire XAML for the comboBox in question:

        <ComboBox x:Name="comboBoxFromMonth" Grid.Row="1" Grid.Column="1" 
Height="24" Width="80" MaxDropDownHeight="520" HorizontalAlignment="Left" 
VerticalAlignment="Center" Margin="4">
            <ComboBox.ItemTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding}" Height="20" />
                </DataTemplate>
            </ComboBox.ItemTemplate>
        </ComboBox>

…(January, February, and December still do not display without scrolling, although there is plenty of room below – real estate is not the problem).

It would seem all items in a comboBox should display BY DEFAULT, not require jumping through hoops to get it all to display…at least with a reasonable amount of items (42 or fewer).

Answer 1

For (a), you’re right, you can use MaxDropDownHeight, but it will only go to the top/bottom of the screen, and no further. To make it fill the screen vertically, you’ll need to modify the default Control Template and give the Popup’s Placement property a different value (eg, Center):

For (b) you can reduce the space between elements by defining an ItemTemplate:

<ComboBox>
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding}" Height="15" />
        </DataTemplate>
    </ComboBox.ItemTemplate>
</ComboBox>