//if add process is clicked this event is triggered.
private void AddProcess_click(object sender, RoutedEventArgs e)
{
List <Process> selectedProcesses = ProcessList.SelectedItems.OfType <Process>().ToList();
List <Category> selectedCategories = CategoryList.SelectedItems.OfType <Category>().ToList();
var processName = selectedProcesses[0].ProcessName;
processController.AddProcessToCategory(selectedCategories[0].Id, selectedProcesses[0].Id, selectedProcesses[0].ProcessName);
}