IfcDoc.CtlRules.UpdateCommands C# (CSharp) Method

        private void UpdateCommands()
        {
            if (this.m_template == null)
            {
                this.toolStripButtonTemplateInsert.Enabled = false;
                this.toolStripButtonTemplateRemove.Enabled = false;
                this.toolStripButtonTemplateUpdate.Enabled = false;
                return;
            }

            bool locked = (this.treeViewTemplate.SelectedNode != null && this.treeViewTemplate.SelectedNode.ForeColor == Color.Gray);

            bool insert = true;
            if (this.treeViewTemplate.SelectedNode != null && this.treeViewTemplate.SelectedNode.Tag is DocModelRuleConstraint)
            {
                insert = false;
            }

            this.toolStripButtonTemplateInsert.Enabled = insert;
            this.toolStripButtonTemplateRemove.Enabled = (this.Selection != null && !locked) || (this.treeViewTemplate.SelectedNode != null && this.treeViewTemplate.SelectedNode.Tag is DocTemplateDefinition);
            this.toolStripButtonTemplateUpdate.Enabled = ((this.Selection is DocModelRuleAttribute || (this.Selection is DocModelRuleEntity)) && !locked);
            this.toolStripButtonRuleRef.Enabled = (this.Selection is DocModelRuleEntity);

            TreeNode tnSelect = this.treeViewTemplate.SelectedNode;
            TreeNode tnParent = null;
            if(tnSelect != null)
            {
                tnParent = this.treeViewTemplate.SelectedNode.Parent;
            }

            this.toolStripButtonMoveUp.Enabled = (tnParent != null && tnParent.Nodes.IndexOf(tnSelect) > 0) && !locked;
            this.toolStripButtonMoveDown.Enabled = (tnParent != null && tnParent.Nodes.IndexOf(tnSelect) < tnParent.Nodes.Count - 1) && !locked;
            this.toolStripButtonSetDefault.Enabled = (this.Selection is DocModelRuleAttribute || this.Selection is DocModelRuleEntity);
        }