public void Add()
        {
            ModalWorkItemDialog dialog = new ModalWorkItemDialog();
            var coWorker = DataContext as CoWorker;
            var workItem = new WorkItem()
                                    {
                                        CoWorkerId = coWorker.CoWorkerId
                                    };

            dialog.DataContext = workItem;
            dialog.ShowDialog();
        }
        public void Edit()
        {
            var coWorker = DataContext as CoWorker;
            ModalWorkItemDialog dialog = new ModalWorkItemDialog();
            var workItem = new WorkItem(coWorker.WorkItems.SelectedItem);
            workItem.OperationState = OperationState.Edit;
            dialog.DataContext = workItem;
            //Get index so we know what to update later.
            int indexOf = coWorker.WorkItems.IndexOf(coWorker.WorkItems.SelectedItem);

            if (dialog.ShowDialog().IsTrue())
            {
                coWorker.WorkItems[indexOf] = dialog.DataContext as WorkItem;
            }
        }