Select the first node as the real first node

tree.go

@@ -50,7 +50,7 @@ func (tree *TreeWidget) Draw(buffer *termui.Buffer) {
 func (tree *TreeWidget) AddRootNode(node *Node) {
 	tree.rootNodes = append(tree.rootNodes, node)
 	if len(tree.rootNodes) == 1 {
-		tree.selectedNode = node.children[0]
+		tree.selectedNode = node
 	}
 	node.setTree(tree)
 }