prs/prs.desktop/Components/EmployeeSelector/EmployeeSelector.xaml

<UserControl x:Class="PRSDesktop.EmployeeSelector"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:local="clr-namespace:PRSDesktop"
             xmlns:Syncfusion="http://schemas.syncfusion.com/wpf"
             mc:Ignorable="d"
             d:DesignHeight="600" d:DesignWidth="200">
       <Grid x:Name="EmployeeGrid" Margin="5,0,0,0" >
            <Grid.RowDefinitions>
                <RowDefinition Height="Auto" />
                <RowDefinition Height="100" x:Name="TeamListRow"/>
                <RowDefinition Height="4" x:Name="TeamListSplitterRow"/>
                <RowDefinition Height="*" />
            </Grid.RowDefinitions>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto" />
                <ColumnDefinition Width="*" />
            </Grid.ColumnDefinitions>
           
            <ComboBox Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="2" x:Name="Teams" DisplayMemberPath="Value" SelectedValuePath="Key"
                      SelectionChanged="TeamsSelectionChanged" VerticalAlignment="Center" Margin="0,0,0,4" />

            <Syncfusion:CheckListBox Grid.Row="1" Grid.ColumnSpan="2" x:Name="TeamList" DisplayMemberPath="Value"
                                     SelectedValuePath="Key" IsSelectAllEnabled="False" IsCheckOnFirstClick="True"
                                     Margin="0,0,0,0" 
                                     ItemChecked="SelectedTeams_ItemChecked"
                                     SizeChanged="SelectedTeams_SizeChanged" />

            <Syncfusion:SfGridSplitter Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="2"
                                       ResizeBehavior="PreviousAndNext" Height="4" HorizontalAlignment="Stretch"
                                       Background="Transparent" Template="{StaticResource HorizontalSplitter}">

                <Syncfusion:SfGridSplitter.PreviewStyle>
                    <Style TargetType="Control">
                        <Setter Property="Background" Value="Gray" />
                        <Setter Property="Template">
                            <Setter.Value>
                                <ControlTemplate TargetType="Control">
                                    <Grid x:Name="Root" Opacity="0.5">
                                        <Rectangle Fill="{TemplateBinding Background}" />
                                    </Grid>
                                </ControlTemplate>
                            </Setter.Value>
                        </Setter>
                    </Style>
                </Syncfusion:SfGridSplitter.PreviewStyle>

            </Syncfusion:SfGridSplitter>

            <Syncfusion:CheckListBox Grid.Row="3" Grid.ColumnSpan="2" x:Name="SelectedEmployees"
                                     DisplayMemberPath="Value" SelectedValuePath="Key" IsSelectAllEnabled="False" IsCheckOnFirstClick="True"
                                     Margin="0,0,0,0" 
                                     ItemChecked="SelectedEmployees_OnItemChecked" />
            
        </Grid>

</UserControl>