Changes of ImageIndex/SelectedImageIndex are slow because FlyGrid needs to repaint images on the screen. Use following code to increase speed of updates:
[c#]
this.treeTest.BeginInit();
try
{
foreach (TreeViewNode node in this.treeTest.Rows.SelectedNodes)
{
node.ImageIndex = 1;
node.SelectedImageIndex = 1;
}
}
finally
{
this.treeTest.EndInit();
}