Update 3
Since you are using MvvmLight: in NoteView, try changing
DataContext="{Binding Note, Source={StaticResource Locator}}"
to
<UserControl.Style>
<Style TargetType="UserControl">
<Setter Property="DataContext" Value="{Binding Note, Source={StaticResource Locator}}"/>
</Style>
</UserControl.Style>
Update 2
, , , , . , ?
<v:NoteView DataContext="{Binding RelativeSource={RelativeSource AncestorType={x:Type Popup}},
Path=DataContext.SelectedNote}"/>
. NoteView. DataContextChangedHandler, ListView?
public NoteView()
{
InitializeComponent();
DependencyPropertyDescriptor dpd =
DependencyPropertyDescriptor.FromProperty(UserControl.DataContextProperty,
typeof(UserControl));
if (dpd != null)
{
dpd.AddValueChanged(this, new EventHandler(DataContextChangedHandler));
}
}
void DataContextChangedHandler(object sender, EventArgs e)
{
MessageBox.Show("DataContext Changed: " + DataContext);
}
DockPanel NoteViewModel DataContext, ListView, DataContext , NoteViewModel DataContext. ListView DataContext , . , DataContext Binding StackPanel, - .
<DataTemplate DataType="{x:Type vm:NoteViewModel}">
<DockPanel>
<TextBlock Text="{Binding Title}" />
<Popup Placement="Right"
PlacementTarget="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=ListViewItem}}"
IsOpen="{Binding (ListViewItem.IsSelected), RelativeSource={RelativeSource FindAncestor, AncestorType=ListViewItem}}"
DataContext="{Binding Path=DataContext, RelativeSource={RelativeSource AncestorType={x:Type ListView}}}">
<StackPanel>
<TextBlock Text="{Binding SelectedNote.Title}" />
<StackPanel>
<v:NoteView DataContext="{Binding SelectedNote}"/>
</StackPanel>
</StackPanel>
</Popup>
</DockPanel>
</DataTemplate>