Follow up from https://www.noesisengine.com/forums/viewtopic.php?f=3&t=1714

So we have a code like this

xaml
<Grid>
<ContentControl Content="{Binding CurrentItem}" />
</Grid>

C++
class ItemVM : public BaseComponent, public INotifyPropertyChanged
{
...
}

class BindingCollectionVM : public BaseComponent, public INotifyPropertyChanged
{
public:
Ptr<ItemVM> m_item = MakePtr<ItemVM>(); // create ItemVM here

void ButtonCmd() {
    m_item.Reset();  // Clear the item when a button is clicked
    _propertyChanged(this, NSS(CurrentItem));
}

NS_IMPLEMENT_INLINE_REFLECTION(BindingCollectionVM, BaseComponent)
{
    ...
    NsProp("CurrentItem", &BindingCollectionVM::m_item );
}

We expect that when the ButtonCmd is fired, m_item is reset, then the ItemVM instance we created will be destroyed. However, it seems that the FrameworkElement still hold the reference preventing the destruction.

(as for the appearance, the ItemVM is correctly disappeared from the UI after the reset)

If for example, we create another instance of ItemVM and assign it to m_item, then the previous instance is correctly destroyed.

void ButtonCmd() {
    m_item = MakePtr<ItemVM>();
    _propertyChanged(this, NSS(CurrentItem));
}