<Window.DataContext>
        <local:ShellViewModel/>
    </Window.DataContext>

    <Window.Resources>
        <conv:BooleanToHiddenVisibility x:Key="boolToVis"/>
    </Window.Resources>

    <Grid x:Name="LayoutRoot">
        <UserControl>
            <UserControl.Resources>
                <DataTemplate x:Key="ItemTemplateKey">
                    <Grid>
                        <Label x:Name="Graph" 
                               Content="{Binding Title}"  
                               Width="{Binding Width}" 
                               Height="{Binding Height}" BorderThickness="2" BorderBrush="Black" Background="Aqua" >
                            <i:Interaction.Behaviors>
                                <il:MouseDragElementBehavior/>
                            </i:Interaction.Behaviors>
                            <i:Interaction.Triggers>
                                <i:EventTrigger EventName="MouseDoubleClick">
                                    <cmd:EventToCommand Command="{Binding DataContext.EditShapeCommand, 
                                                        RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ItemsControl}}}"
                                                        CommandParameter="{Binding}"/>
                                </i:EventTrigger>
                            </i:Interaction.Triggers>
                        </Label>
                    </Grid>
                </DataTemplate>
            </UserControl.Resources>

            <Grid x:Name="LayoutRoot2">
                <ItemsControl
                    ItemsSource="{Binding GraphCollection}"
                    ItemTemplate="{StaticResource ItemTemplateKey}">
                    <ItemsControl.ItemsPanel>
                        <ItemsPanelTemplate>
                            <Canvas IsItemsHost="True" Background="LightGray">
                                <i:Interaction.Triggers>
                                    <i:EventTrigger EventName="MouseLeftButtonDown">
                                        <cmd:EventToCommand Command="{Binding AddShapeCommand}" PassEventArgsToCommand="True"/>
                                    </i:EventTrigger>
                                </i:Interaction.Triggers>
                            </Canvas>
                        </ItemsPanelTemplate>
                    </ItemsControl.ItemsPanel>
                    <ItemsControl.ItemContainerStyle>
                        <Style>
                            <Setter Property="Canvas.Left" Value="{Binding X}"/>
                            <Setter Property="Canvas.Top" Value="{Binding Y}"/>
                        </Style>
                    </ItemsControl.ItemContainerStyle>
                </ItemsControl>
            </Grid>
        </UserControl>
    </Grid>

public class ShellViewModel : ViewModelBase
    {
        
        public bool IsShape { get; set; }
        public ObservableCollection<GraphElement> GraphCollection { get; set; }

        private RelayCommand<GraphElement> _editShapeCommand;

        public RelayCommand<GraphElement> EditShapeCommand
        {
            get { return _editShapeCommand ?? (_editShapeCommand = new RelayCommand<GraphElement>(EditShape)); }
        }

        private void EditShape(GraphElement i)
        {
            IsShape = true;
            i.EditMode = !i.EditMode;
        }

        private RelayCommand<object> _addShapeCommand;

        public RelayCommand<object> AddShapeCommand
        {
            get { return _addShapeCommand ?? (_addShapeCommand = new RelayCommand<object>(AddShape)); }
        }

        private void AddShape(object param)
        {
            if (IsShape)
            {
                IsShape = false;
                return;
            }
            var mouseButtonEventArgs = param as MouseButtonEventArgs;
            if (mouseButtonEventArgs == null) return;
            var point = mouseButtonEventArgs.GetPosition((UIElement)mouseButtonEventArgs.OriginalSource);

            if (mouseButtonEventArgs.ClickCount == 2)
            {
                var graph = new GraphElement() { X = point.X, Y = point.Y };
                GraphCollection.Add(graph);
            }
        }

        public ShellViewModel()
        {
            GraphCollection = new ObservableCollection<GraphElement>();
        }
    }