kevinshaffer said:

Hopefully this will help someone else who struggles with making this work.

Thank's alot for sharing! :)

Hello,

Here is and another approach for this functionality with recursive methods.  

Please let me know if you have any further questions.

Hopefully this will help someone else who struggles with making this work. I needed to have all nodes be able to be checked, not just nodes who have no children. Also, parent nodes should appear as indeterminate when some (but not all) of their children are checked. However, when a user checks a node that is indeterminate, it needs to go back to switching between checked and unchecked. The following is the code I came up with:

private void treeView_AfterCheck(object sender,
                                 NodeEventArgs e)
{
  if (e.TreeNode.CheckedState !=
      CheckState.Indeterminate)
  {
    e.TreeNode.Override.NodeStyle =
      NodeStyle.CheckBox;

    foreach (UltraTreeNode childNode
             in e.TreeNode.Nodes)
    {
      childNode.CheckedState =
        e.TreeNode.CheckedState;
    }
  }
  if (e.TreeNode.Parent != null &&
      e.TreeNode.Parent.CheckedState !=
        e.TreeNode.CheckedState)
  {
    if (e.TreeNode.CheckedState ==
        CheckState.Indeterminate)
    {
      e.TreeNode.Parent.CheckedState =
        CheckState.Indeterminate;
    }
    else
    {
      bool indeterminate = false;
      foreach (UltraTreeNode siblingNode
               in e.TreeNode.ParentNodesCollection)
      {
        if (siblingNode.CheckedState !=
            e.TreeNode.CheckedState)
        {
          indeterminate = true;
          break;
        }
      }
      e.TreeNode.Parent.CheckedState =
        indeterminate ?
        CheckState.Indeterminate :
        e.TreeNode.CheckedState;
    }
  }
}
private void treeView_BeforeCheck(object sender,
                                  BeforeCheckEventArgs e)
{
  if (e.NewValue == CheckState.Indeterminate &&
      e.TreeNode.Override.NodeStyle !=
        NodeStyle.CheckBoxTriState)
  {
    e.TreeNode.Override.NodeStyle =
      NodeStyle.CheckBoxTriState;
  }
}

Sorry for having to keep the lines so short so the post fits