ComboBox Size Differences - wpf

Question

I have 2 ComboBox's in a app settings flyout. One of which has an ItemTemplate defined and the other does not:
<StackPanel Orientation="Horizontal"
Margin="5">
<Label Content="Accent"
VerticalAlignment="Center"/>
<ComboBox ItemsSource="{Binding MetroAccents}"
SelectedItem="{Binding SelectedAccent}"
Margin="5">
<ComboBox.ItemTemplate>
<DataTemplate>
<Label Content="{Binding Name}"
Margin="0"/>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
<StackPanel Orientation="Horizontal"
Margin="5">
<Label Content="Grid Lines"
VerticalAlignment="Center"/>
<ComboBox ItemsSource="{Binding GridLinesVisibilityList}"
SelectedItem="{Binding SelectedGridLinesVisibility}"
Margin="5"/>
However, the ComboBox with the ItemTemplate has a larger height than the other ComboBox. Analysing the control with the 'Enable Selection' debugging tool, the ComboBox with the ItemTemplate seems to have a TextBlock with the Label (defined in the template). Whereas the other ComboBox only has a Label. Does anyone know why this is?

Answer 1

Label will take more space due to it's default style which looks like this:
<Style x:Key="LabelStyle1" TargetType="{x:Type Label}">
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="Padding" Value="5"/>
<Setter Property="HorizontalContentAlignment" Value="Left"/>
<Setter Property="VerticalContentAlignment" Value="Top"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Label}">
<Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true">
<ContentPresenter HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" RecognizesAccessKey="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Which as you can see has padding on it. While the TextBlock does not. This is why it takes more space.
Bear in mind that Label supports key bindings with _ underscore and also other UI elements as it's content. I personally don't use it unless I need key bindings, but even then I use AccessText MSDN.