I had this problem myself the other day and it seems that all the solutions I found where mostly javascript based. But this is not a good solution in my mind, therefore I did some reflection and came up with this solution, all server side.
public override ToolPart[] GetToolParts()
{
var list = new List<ToolPart>(base.GetToolParts());
foreach (var wptp in list.OfType<WebPartToolPart>())
{
HideExpandIndexes(wptp);
}
return list.ToArray();
}
private void HideExpandIndexes(WebPartToolPart part)
{
var field_helper = part.GetType().GetField("_helper", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.FlattenHierarchy);
var _helper = field_helper.GetValue(part);
var field_expandIndexes = _helper.GetType().BaseType.GetField("_expandIndexes", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.FlattenHierarchy);
var _expandIndexes = field_expandIndexes.GetValue(_helper);
var field_items = _expandIndexes.GetType().GetField("_items", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.FlattenHierarchy);
var _items = (Hashtable)field_items.GetValue(_expandIndexes);
_items.Clear();
}
The code can be improved to a finer detail, but it solves the problem for the moment.
