<telerik:RadTreeView x:Name="treeView" 
                         CheckBoxMode="Recursive" Grid.Row="1"
                         SelectedItems="{Binding CheckedItems, Mode=TwoWay}"
                          ItemsSource="{Binding Items}">

<telerik:RadTreeView x:Name="treeView" 
                         CheckBoxMode="Recursive" Grid.Row="1"
                              ItemsSource="{Binding Items}"
                         SelectedItems="{Binding CheckedItems, Mode=TwoWay}">

            <treeview:TreeViewDescriptor
			ItemsSourcePath="Children"
			TargetType="{x:Type models:Folder}">
                <treeview:TreeViewDescriptor.ItemTemplate>
                    <DataTemplate>
                        <Grid ColumnDefinitions="Auto, *, Auto">

                            <Label
				Grid.Column="0"
				FontFamily="MaterialIcons"
				FontSize="22.0"
				Text="Folder"
				TextColor="Peru"
				VerticalOptions="Center" />

                            <Label
				Grid.Column="1" 
				Margin="6.0,0.0"
				LineBreakMode="TailTruncation"
				Text="Item with loooooooooooooooong naaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaammmmmmmmmmmmmmeeeeeeeeeeeeee"
				VerticalOptions="Center" />

                            <Button Text=". . ."
				Grid.Column="2"
				BackgroundColor="Transparent"
				WidthRequest="64.0">
                            </Button>
                        </Grid>
                    </DataTemplate>
                </treeview:TreeViewDescriptor.ItemTemplate>
            </treeview:TreeViewDescriptor>