TreeView item foreground binding MVVM

Question

I am using TreeView to display my data. I want to bind foreground of a tree view item. Here is my code below.

View:

<UserControl.Resources>
    <HierarchicalDataTemplate x:Key="TreeViewItem" ItemsSource="{Binding Children}">
        <StackPanel Orientation="Horizontal">
            <CheckBox Margin="2" IsChecked="{Binding IsChecked, Mode=TwoWay}" Content="{Binding Title}" 
                        Background="{Binding Path=ForegroundColor}" IsThreeState="True"/>
        </StackPanel>
    </HierarchicalDataTemplate>
</UserControl.Resources>
<Grid>
    <TreeView Margin="5, 0, 5, 0" ItemsSource="{Binding GeoGraphixModules}" ItemTemplate="{StaticResource TreeViewItem}" IsEnabled="{Binding TreeViewEnabled}" />
</Grid>

And in my view model

public class SomeTreeViewItem { public Collection Children { get { return _children; } }

public Brush ForegroundColor
{
    get
    {
        if (SomeCheck)
            return Brushes.Green;
        else
            return Brushes.Red;
    }
}    

}

Now when I debug this application 'ForegroundColor' is hit but the application still displays black as foreground for all the child items. What is the problem here?

Answer 1

After trying to create the same error i made the following viewmodel

public class ViewModel
{
    private Collection<GeoGraphixModule> _geoGraphixModules;

    public ViewModel()
    {
        _geoGraphixModules = new Collection<GeoGraphixModule>();
        _geoGraphixModules.Add(new GeoGraphixModule(){Children = new Collection<Bla>(){new Bla{Children = new Collection<Bla>{new Bla(), new Bla(), new Bla()}}}});
        _geoGraphixModules.Add(new GeoGraphixModule(){Children = new Collection<Bla>(){new Bla{Children = new Collection<Bla>{new Bla(), new Bla(), new Bla()}}}});
        _geoGraphixModules.Add(new GeoGraphixModule(){Children = new Collection<Bla>(){new Bla{Children = new Collection<Bla>{new Bla(), new Bla(), new Bla()}}}});
        _geoGraphixModules.Add(new GeoGraphixModule(){Children = new Collection<Bla>(){new Bla{Children = new Collection<Bla>{new Bla(), new Bla(), new Bla()}}}});
    }

    public Collection<GeoGraphixModule> GeoGraphixModules
    {
        get { return _geoGraphixModules; }
        set { _geoGraphixModules = value; }
    }
}

public class GeoGraphixModule
{
    public Brush ForegroundColor
    {
        get
        {
            if (SomeCheck())
                return Brushes.Green;
            return Brushes.Red;
        }
    }

    private bool SomeCheck()
    {
        Random random = new Random();
        int randomNumber = random.Next(0, 100);

        if ((randomNumber % 2) == 0)
            return true;
        return false;
    }

    private Collection<Bla> _children;
    public Collection<Bla> Children { get; set; }
}

public class Bla
{
    private bool? _isChecked;
    private string _title;
    private Collection<Bla> _children;

    public bool? IsChecked
    {
        get { return _isChecked; }
        set
        {
            _isChecked = value;
        }
    }

    public Collection<Bla> Children
    {
        get { return _children; }
        set { _children = value; }
    }

    public string Title
    {
        get { return _title; }
        set
        {
            _title = value;
        }
    }
}

Its very ugly i know but it works for the top level take a loot at the below image