private void UpdateUI()
{
List <string> expandedNodes = Helpers.GetExpandedNodes(TreeViewItems.Nodes);
// Dirty trick to prevent flickering
this.BackgroundImage = new Bitmap(TreeViewItems.Width, TreeViewItems.Height);
TreeViewItems.DrawToBitmap((Bitmap)this.BackgroundImage, new Rectangle(TreeViewItems.Location, TreeViewItems.Size));
TreeViewItems.Visible = false;
TreeViewItems.BeginUpdate();
TreeViewItems.Nodes.Clear();
foreach (Group g in groups.OrderBy(grp => grp.Name))
{
AddGroupNode(g, null);
}
if (selectedNode != null)
{
SelectNode(TreeViewItems.Nodes, selectedNode.Text);
}
Helpers.SetExpandedNodes(TreeViewItems.Nodes, expandedNodes);
TreeViewItems.EndUpdate();
TreeViewItems.Visible = true;
this.BackgroundImage = null;
}