Expander Header Height

[xperia-droid]

Hi,
i just want to adjust the Expander Header Height Value, so that's it smaller, as ~ 40 pixel.

I added the materialDesign Expander in my app.xaml and the MaterialDesignHorizontalHeaderStyle into it, but I don't found any way to make the Header smaller.

I tried different properties, but no change at all.

`<Style x:Key="CustomHeader" TargetType="{x:Type ToggleButton}">

            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type ToggleButton}">
                        <Border Padding="{Binding Path=(wpf:ExpanderAssist.HorizontalHeaderPadding), RelativeSource={RelativeSource AncestorType=Expander, AncestorLevel=1}}" Background="{TemplateBinding Background}">
                            <Grid>
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition Width="*" />
                                    <ColumnDefinition Width="16" />
                                    <ColumnDefinition Width="Auto" />
                                </Grid.ColumnDefinitions>

                                <ContentPresenter Grid.Column="0"
                            VerticalAlignment="Center"
                            Content="{TemplateBinding Content}"
                            ContentStringFormat="{TemplateBinding ContentStringFormat}"
                            ContentTemplate="{TemplateBinding ContentTemplate}"
                            ContentTemplateSelector="{TemplateBinding ContentTemplateSelector}" />

                                <ToggleButton x:Name="ExpanderButton"
                        Grid.Column="2"
                        VerticalAlignment="Center"
                        Foreground="{TemplateBinding Foreground}"
                        IsChecked="{Binding Path=IsChecked, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}"
                        RenderTransformOrigin="0.5 0.5">
                                    <ToggleButton.Style>
                                        <Style TargetType="{x:Type ToggleButton}" BasedOn="{StaticResource MaterialDesignExpanderToggleButton}">
                                            <Style.Triggers>
                                                <DataTrigger Binding="{Binding ExpandDirection, RelativeSource={RelativeSource AncestorType=Expander, AncestorLevel=1}}" Value="Up">
                                                    <Setter Property="RenderTransform">
                                                        <Setter.Value>
                                                            <RotateTransform Angle="180" />
                                                        </Setter.Value>
                                                    </Setter>
                                                </DataTrigger>
                                            </Style.Triggers>
                                        </Style>
                                    </ToggleButton.Style>
                                </ToggleButton>
                            </Grid>
                        </Border>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>

        <Style TargetType="{x:Type Expander}" x:Key="CustomExpanderStyle" BasedOn="{StaticResource MaterialDesignExpander}">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type Expander}">
                        <Border x:Name="Bd" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}">
                            <Grid>
                                <Grid.RowDefinitions>
                                    <RowDefinition Height="50" />
                                    <RowDefinition Height="*" />
                                </Grid.RowDefinitions>
                                <ToggleButton x:Name="HeaderSite" Grid.Row="0" Content="{TemplateBinding Header}" IsChecked="{Binding IsExpanded, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Style="{StaticResource CustomHeader}"/>
                                <ContentPresenter x:Name="ExpandSite" Grid.Row="1" Visibility="Collapsed" Content="{TemplateBinding Content}" ContentTemplate="{TemplateBinding ContentTemplate}"/>
                            </Grid>
                        </Border>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>`

Thank you very much for your help :).

[nicolaihenriksen]

@xperia-droid Looking at the code you provided, one problem could be that you have given your Expander style and explicit key (i.e. "CustomExpanderStyle" string) rather than an implicit key (Expander type). When doing that, you will need to manually apply that custom style on every Expander instance by setting the Style property with something akin to {StaticResource CustomExpanderStyle}.

To avoid having to do that, you should be able to rely on the implicit style, so basically this part:

<Style TargetType="{x:Type Expander}" x:Key="CustomExpanderStyle" BasedOn="{StaticResource MaterialDesignExpander}">

Should be (i.e. without the x:key="CustomExpanderStyle"):

<Style TargetType="{x:Type Expander}" BasedOn="{StaticResource MaterialDesignExpander}">