OnlineMonitorSystem/HandyControl/HandyControl_Shared/Themes/Styles/TreeView.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <Style BasedOn="{StaticResource TreeViewItemBaseStyle}" TargetType="TreeViewItem"/>

    <Style BasedOn="{StaticResource TreeViewBaseStyle}" TargetType="TreeView"/>

    <Style x:Key="TreeViewItemBaseStyle.Small" BasedOn="{StaticResource TreeViewItemBaseStyle}" TargetType="TreeViewItem">
        <Setter Property="Padding" Value="6,0"/>
        <Setter Property="MinHeight" Value="24"/>
    </Style>

    <Style x:Key="TreeView.Small" BasedOn="{StaticResource TreeViewBaseStyle}" TargetType="TreeView">
        <Setter Property="ItemContainerStyle" Value="{StaticResource TreeViewItemBaseStyle.Small}"/>
    </Style>

</ResourceDictionary>