private void RemoveSkillFromPreferred()
 {
     if (SelectedSkillToRemove != null)
     {
         UnselectedSkillList.Add(SelectedSkillToRemove);
         ContractorHasSkillList.Remove(SelectedSkillToRemove);
         SelectedSkillToAdd    = null;
         SelectedSkillToRemove = null;
     }
 }
 private void AddSkillToPreferred()
 {
     if (SelectedSkillToAdd != null)
     {
         ContractorHasSkillList.Add(SelectedSkillToAdd);
         UnselectedSkillList.Remove(SelectedSkillToAdd);
         SelectedSkillToAdd    = null;
         SelectedSkillToRemove = null;
     }
 }