WPF/MVVM - how to handle double-click on TreeViewItems in the ViewModel?

Question

(Note - this is a re-post as my first question got posted under wrong headline: Here Sorry!)

I have a standard WPF treeview and have bound items to view model classe

Answer 1

It is really simple and this is how I handled double click at the TreeView:

System.Windows.Interactivity.dll is taken from C:\Program Files (x86)\Microsoft SDKs\Expression\Blend.NETFramework\v4.0\Libraries\System.Windows.Interactivity.dll or by NuGet

My view model:

public class TreeViewModel : INotifyPropertyChanged
{   
    private List departments;
    public TreeViewModel()
    {
        Departments = new List()
        {
            new Department("Department1"),
            new Department("Department2"),
            new Department("Department3")
        };
    }

    public List Departments
    {
        get
        {
            return departments;
        }
        set
        {
            departments = value;
            OnPropertyChanged("Departments");
        }
    }

    public void SomeMethod()
    {
        MessageBox.Show("*****");
    }
}