WPF binded Listbox bug when display 2 items - wpf

Question

I have a WPF listbox in my window. In the Load event of the window, i create a List(of Object) and I added some items. At application starts or debug, I can see items.
If I add 1 item on the list, i correctly see 1 only item. If I add 3 or more items, i correctly see 3 or more items. If I add 2 only items, i see 1 only item. Why?
Here is my WPF code
<Window x:Class="Cacatua.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:Cacatua;assembly=" >
<Grid>
<ListBox Name="lbSearch" ItemsSource="{Binding}" />
</Grid>
</Window>
And here is my code-behind (same assembly, in Cacatua namespace):
Private myLstSearch As List(Of Object)
Private Sub Window_Loaded(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
myLstSearch = New List(Of Object)
lbSearch.ItemsSource = myLstSearch
Dim myMedia1 as Media1
myMedia1 = New Media1("IdMedia1-A")
myLstSearch.Add(myMedia1)
myMedia1 = New Media1("IdMedia1-B")
myLstSearch.Add(myMedia1)
End Sub
where Media1 is a simple class that contains a string
Public Class Media1
Private myIdTitolo As String
Public ReadOnly Property IDTitolo As String
Get
Return (myIdTitolo)
End Get
End Property
Public Sub New(str As String)
myIdTitolo = str
End Sub
End Class
With this code, I would see a list with this output (there is no datatemplate):
Cacatua.Media1
Cacatua.Media1
but I see only
Cacatua.Media1
I think it's a bug. But am I the first with this problem?

Answer 1

You've got the right idea, but the problem is your ItemsSource doesn't know when to update since you're not using an ObservableCollection. Also there is a timing issue between rendering and loading the window, and I think this has to do with the fact you aren't properly binding your items source.
For starters, try changing the type of myLstSearch to ObservableCollection(Of Media1).
Also, a better way to do this would be to databind it from the XAML directly, so your code-behind would be something like:
Public property MyListSearch As ObservableCollection(Of Media1)
Then your XAML would look like:
<Window x:Class="Cacatua.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:Cacatua;assembly=">
<Grid>
<ListBox Name="lbSearch" ItemsSource="{Binding Path=MyListSearch}" />
</Grid>
</Window>
That way, you can simply initialize MyListSearch in your window constructor, and then add elements to it whenever, while your view will automatically update.