protected override void OnKeyDown(KeyEventArgs e)
{
e.Handled = e.SuppressKeyPress = true;
if (e.Alt && (e.KeyCode == Keys.Down)) {
DroppedDown = true;
}
else if ((e.KeyCode == Keys.Up) || (e.KeyCode == Keys.Left)) {
ComboTreeNode prev = GetPrevDisplayedNode();
if (prev != null) SetSelectedNode(prev);
}
else if ((e.KeyCode == Keys.Down) || (e.KeyCode == Keys.Right)) {
ComboTreeNode next = GetNextDisplayedNode();
if (next != null) SetSelectedNode(next);
}
else {
e.Handled = e.SuppressKeyPress = false;
}
base.OnKeyDown(e);
}