private void button_Add(BoxExchangeEditor bx, List<string> src)
{
int pos = bx.SourceBox.SelectedIndex - bx.SourceBox.SelectedItems.Count;
bx.addItems(bx.SourceBox, bx.TargetBox);
reLoadButtonItem(bx, src);
if (bx.SourceBox.Items.Count != 0)
{
pos = pos <= 1 ? 1 : pos;
pos = Math.Max(0, Math.Min(pos, bx.SourceBox.Items.Count - 1));
bx.SourceBox.SelectedIndex = pos - 1;//順序がヘンだが、ENTERの場合はこの後に+1処理が入る模様
}
}