Hi Jack.
Trust me to try a new version...
With EO version 2012, there appears to be a problem (javascript error) if a treeview is embedded in a callback panel and the code behind attempts to set a style for a treenode.
Sample code: what is shown below demonstrates the error, but when the code line that sets the normal style of the primary node (primarynode.NormalStyle = primarystyle) is commented out no error occurs
Code: C#
if (!IsPostBack)
{
// just try adding a node...
ElementStyle primarystyle = new ElementStyle();
primarystyle.CssText = "{ FONT-WEIGHT:bold; FONT-SIZE: 12pt; font-family:Arial;}";
tvQualifications.Nodes.Clear(); // clear all nodes from the treeview
EO.Web.TreeNode primarynode = new EO.Web.TreeNode("Some text...");
primarynode.NormalStyle = primarystyle;
primarynode.ShowCheckBox = true;
tvQualifications.Nodes.Add(primarynode);