int intEnd = citiesBindingSource.Count - 1;

switch (this.citiesBindingSource.Position)
			{
				case intEnd:
					bindingNavigatorMoveFirstItem.Enabled = true;
					NavPrevGroup.Enabled = true;
					bindingNavigatorMovePreviousItem.Enabled = true;

					bindingNavigatorMoveNextItem.Enabled = false;
					NavNextGroup.Enabled = false;
					bindingNavigatorMoveLastItem.Enabled = false;
					break;

				case 0: 
					bindingNavigatorMoveFirstItem.Enabled = false;
					NavPrevGroup.Enabled = false;
					bindingNavigatorMovePreviousItem.Enabled = false;

					bindingNavigatorMoveNextItem.Enabled = true;
					NavNextGroup.Enabled = true;
					bindingNavigatorMoveLastItem.Enabled = true;
					break;

				default:
					bindingNavigatorMoveFirstItem.Enabled = true;
					NavPrevGroup.Enabled = true;
					bindingNavigatorMovePreviousItem.Enabled = true;

					bindingNavigatorMoveNextItem.Enabled = true;
					NavNextGroup.Enabled = true;
					bindingNavigatorMoveLastItem.Enabled = true;
					break;
			}