public PackageGroup(string groupName, bool hidden = false) { name = groupName; root = Resources.GetTemplate("PackageGroup.uxml"); Add(root); HeaderTitle.text = groupName; HeaderTitle.ShowTextTooltipOnSizeChange(); if (hidden) { HeaderContainer.AddToClassList(k_HiddenHeaderClass); } HeaderContainer.RegisterCallback <MouseDownEvent>(TogglePackageGroup); }