dependency property in UserControl

 <UserControl
    x:Class="MyLib.Legend"
             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" 
             mc:Ignorable="d" Height="28" Width="80">
    <Grid  Margin="0,0,0,253">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="50"></ColumnDefinition>
            <ColumnDefinition Width="30"></ColumnDefinition>            
        </Grid.ColumnDefinitions>
        <Label Margin="0,0,0,-25" Content="График 1" />
        <CheckBox  IsChecked="{Binding ElementName=leg2, Path=IsChecked}" Grid.Column="1" HorizontalAlignment="Left" Height="15" Margin="7,7,0,-22" VerticalAlignment="Top" Width="18"/>
    </Grid>
</UserControl>

Legend.xaml.cs


 public partial class Legend :UserControl

    {
      
        public static readonly DependencyProperty IsCheckedProperty = DependencyProperty.Register("IsChecked", typeof(bool), typeof(Legend), null);

        public bool IsChecked
        {
            get { return (bool)GetValue(IsCheckedProperty); }
            set { SetValue(IsCheckedProperty, value); }
        }

        public event RoutedEventHandler IsChecked
        {
            add
            {
                base.AddHandler(Legend.MyClickEvent, value);
            }
           remove
            {
                base.RemoveHandler(Legend.MyClickEvent, value);
            }
        }        

       

        public Legend()
        {
            InitializeComponent();
        }       
    }

MainWindow.xaml

<Window
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"         
        xmlns:oxy="http://oxyplot.codeplex.com" 
        xmlns:Custom="http://infragistics.com/DataPresenter"        
        xmlns:local="clr-namespace:WpfExamples"      
        xmlns:MyLib="clr-namespace:MyLib;assembly=MyLib" 
        xmlns:MyLibrary="clr-namespace:MyLibrary;assembly=MyLibrary" 
        x:Class="WpfExamples.MainWindow"      
        Title="OxyPlot WPF/XAML examples" Height="628.633" Width="1024.91">

    <Grid Margin="0,0,25,48" >
        <Grid.Resources> 
            <local:Title_View2 x:Key="Legend2_View"/>
        </Grid.Resources>
      
        <MyLib:Legend  Name="leg2" HorizontalAlignment="Left" Margin="573,267,0,0" VerticalAlignment="Top"/>
        <Button
            Visibility="{Binding IsChecked, Converter={StaticResource Legend2_View}, ElementName=leg2}" 
            Content="Button" 
            HorizontalAlignment="Left" Margin="591,317,0,0" VerticalAlignment="Top" Width="75"/>

    </Grid>
</Window>

MainWindow.cs

...

  public class Title_View2 : IValueConverter
    {
        public object Convert(object value, Type targetTipe, object parameter, CultureInfo culture)
        {
            if (value is bool)
                return ((bool)value) ? Visibility.Visible : Visibility.Collapsed;

            return Visibility.Collapsed;
        }
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }