Treeview IsSelected with different viewmodel - wpf

Question

I have a treeview binded to an Observablecollection of ParentViewModel.
The ParentViewModel contains an Observablecollection of ChildViewModel.
Both this ViewModel implement an IsSelected property. I put it in both of them because the implementation is a little bit different. The program have to behave differently if I press a Parent or Child item.
My problem is that also if I select a Child item, program execute the IsSelected property of the ParentViewModel, not the one of the ChildViewModel.
This is my XAML:
<TreeView Name="MyTreeView"
ItemsSource="{Binding ParentList}">
<TreeView.ItemContainerStyle>
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
</Style>
</TreeView.ItemContainerStyle>
<TreeView.Resources>
<HierarchicalDataTemplate DataType="{x:Type local:ParentViewModel}" ItemsSource="{Binding Childs}">
<Grid >
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="1*"/>
</Grid.ColumnDefinitions>
<Image Grid.Column="0" Source="{Binding PictureString}" Height="32" Width="32" Margin="0,8,6,4" />
<TextBlock Grid.Column="1" Text="{Binding Name}" FontSize="15" Margin="10" />
</Grid>
<HierarchicalDataTemplate.ItemContainerStyle>
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
</Style>
</HierarchicalDataTemplate.ItemContainerStyle>
</HierarchicalDataTemplate>
<DataTemplate DataType="{x:Type local:ChildViewModel}">
<Grid >
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto"/>
<ColumnDefinition Width="1*"/>
</Grid.ColumnDefinitions>
<!--<Image Grid.Column="0" Source="{Binding PictureString}" Height="32" Margin="0,8,6,4" />-->
<TextBlock Grid.Column="1" Text="{Binding Name}" Height="18" FontSize="15" Margin="10"/>
</Grid>
</DataTemplate>
</TreeView.Resources>
</TreeView>
The program never hit the IsSelected setter of the ChildViewModel.
Thanks in advance
EDIT
This is the BaseViewModel:
Public Class InheritableTreeViewItem
Implements INotifyPropertyChanged
Friend m_Name As String
Public Property Name As String
Get
Return m_Name
End Get
Set(value As String)
If (value <> m_Name) Then
m_Name = value
NotifyPropertyChanged("Name")
End If
End Set
End Property
Friend m_IsSelected As Boolean
Public Overridable Property IsSelected As Boolean
Get
Return m_IsSelected
End Get
Set(value As Boolean)
If (value <> m_IsSelected) Then
m_IsSelected = value
NotifyPropertyChanged("IsSelected")
End If
End Set
End Property
Private m_sPictureString As String
Private m_Items As ObservableCollection(Of InheritableTreeViewItem)
Public Property PictureString As String
Get
Return m_sPictureString
End Get
Set(value As String)
If value <> m_sPictureString Then
m_sPictureString = value
NotifyPropertyChanged("PictureString")
End If
End Set
End Property
Public Property Items As ObservableCollection(Of InheritableTreeViewItem)
Get
Return m_Items
End Get
Set(value As ObservableCollection(Of InheritableTreeViewItem))
m_Items = value
End Set
End Property
Sub New(Name As String)
Me.Name = Name
Me.Items = New ObservableCollection(Of InheritableTreeViewItem)
End Sub
Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged
Public Sub NotifyPropertyChanged(propName As String)
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propName))
End Sub
End Class
And this is the ParentViewModel:
Public Class ParentViewModel
Inherits InheritableTreeViewItem
Public Overrides Property IsSelected As Boolean
Get
Return m_IsSelected
End Get
Set(value As Boolean)
If (value <> m_IsSelected) Then
m_IsSelected = value
If value Then
' The function that I want to call When Parent item is selected in the tree
End If
NotifyPropertyChanged("IsSelected")
End If
End Set
End Property
Sub New(Name As String)
MyBase.New(Name)
Me.PictureString = "/Resources/TreeView/Folder.png"
End Sub
End Class
The ChildViewModel is basically identical, it differs only for the function that I call when it is selected. This function modify the content and visibility of some TextBoxes.

Answer 1

I think your problem is at this block :
<TreeView.ItemContainerStyle>
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
</Style>
</TreeView.ItemContainerStyle>
Because it is a style, I'm not sure that the DataContext is properly inherited. Also why do you redefine this in the HierarchicalDataTemplate? I don't think you need to redefine this style for ChildViewModelItems.
Maybe you could debug your databinding in depth to see what's happening on this property : How to debug data binding.
Also, the plural of Child is Children, not Childs ;)