private void newGroup() {
    this.saveData();
    if (this.currentContainer == null) return;

    DefaultMutableTreeNode node = null;

    ArmylistWargearGroup parentGroup = null;
    if (this.currentContainer.getGroup() != null) {
      parentGroup = this.currentContainer.getGroup();
      node = this.currentContainer.getNode();
    }
    if (parentGroup == null && this.currentContainer.getItemGroup() != null) {
      parentGroup = this.currentContainer.getItemGroup();
      node = this.currentContainer.getParent();
    }
    if (parentGroup == null) return;

    ArmylistWargearGroup newGroup = new ArmylistWargearGroup("new group");

    parentGroup.addSubGroup(newGroup);
    this.addGroupToNode(node, newGroup);
    this.wargearTree.updateUI();
  }