TwoWay Binding of a ComboBox to a static property

Question

-------EDIT------

So, i figured that my code is correct and so are the code snippets from all of your answers. Thanks for that. My

Answer 1

Checked just in a sample project, works fine

public class ViewModel
{
    static ViewModel()
    {
        Items=new ObservableCollection<string>();
        SelectedItem = "222";
        Items.Add("111");
        Items.Add("222");
        Items.Add("333");
        Items.Add("444");
        Items.Add("555");
    }
    private static string _selectedItem;
    public static string SelectedItem
    {
        get { return _selectedItem; }
        set { _selectedItem = value;
            MessageBox.Show("Item " + value + " was selected");
        }
    }

    private static ObservableCollection<string> _items;
    public static ObservableCollection<string> Items
    {
        get { return _items; }
        set { _items = value; }
    }
}

and xaml

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:my="clr-namespace:WpfApplication1"
    Title="MainWindow" Height="200" Width="300">
<Grid>
    <Grid.Resources>
        <my:ViewModel x:Key="viewM"/>
    </Grid.Resources>
    <ComboBox Height="23" HorizontalAlignment="Left" Margin="101,12,0,0" Name="comboBox1" VerticalAlignment="Top" Width="146" 
               ItemsSource="{Binding Source={x:Static my:ViewModel.Items}, Mode=OneWay}"
              SelectedItem="{Binding Source={StaticResource viewM}, Path=SelectedItem}" />
    </Grid>
</Window>

I have uploaded sample.

Answer 2

You're being confused between instances and static properties: you don't need to bind a static object.

<ComboBox
        ItemsSource="{x:Static me:MainWindowViewModel.MyElements}"
        SelectedItem="{x:Static me:MainWindowViewModel.SelectedElement}" />

And you should implement INotifyPropertyChanged nevertheless.

Binding is about resolving the right instance from which you want to fetch data.
If there is no meaning of instance, there is no need for binding.