private void btnEdit_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                string name        = txtName.Text;
                string description = txtDescription.Text;

                Employ   assignee = BoardDB.GetEmployees().ToList().FirstOrDefault(employ => employ.ToString() == cbAssignee.Text);
                DateTime endDate  = (DateTime)pickerDateEnd.SelectedDate;

                Board.CurrentlySelectedTask.task.Name           = name;
                Board.CurrentlySelectedTask.task.Description    = description;
                Board.CurrentlySelectedTask.task.TaskEndDate    = endDate;
                Board.CurrentlySelectedTask.task.LastModifyDate = DateTime.Now;
                Board.CurrentlySelectedTask.task.employId       = assignee.employId;
                Board.CurrentlySelectedTask.task.Estimation     = Board.GetKeyForValue(cbEstimation.Text, Board.Estimates).estimateId;

                Board.CurrentlySelectedTask.employ = assignee;

                Column newColumn = Board.GetKeyForValue(cbColumn.Text, Board.Columns);
                Board.CurrentlySelectedTask.task.columnId = newColumn.columnId;

                BoardDB.GetDB().SaveChanges();
                Board.ClearListsAndRestoreFromDB();

                MainBoardPage boardPage = new MainBoardPage();
                this.NavigationService.Navigate(boardPage);
            }
            catch (InvalidOperationException err)
            {
                lblError.Content = err.Message;
            }
        }
        private void btnBack_Click(object sender, RoutedEventArgs e)
        {
            MainBoardPage boardPage = new MainBoardPage();

            this.NavigationService.Navigate(boardPage);
        }