stride3d/stride · warning · NotSupportedException

Grouping elements into a user library type isn't supported.

Error message

Grouping elements into a user library type isn't supported.

What it means

UIEditorBaseViewModel.GroupInto wraps the selected elements into a new parent panel of the given factory's type. Only system-library panel types are supported; if the factory resolves from a user (custom) library, the target type is null and NotSupportedException is thrown, because instantiating user library types as grouping containers is not implemented.

Solutions

1. Restrict the group-into menu to system-library panel factories (UIElementFromSystemLibrary whose type is a Panel).
2. Group into a built-in panel type such as Grid or StackPanel.
3. Disable or hide the grouping command for user library factories.
4. Extend GroupInto to resolve user library types if grouping into custom panels is required.

Example fix

// before
viewModel.GroupInto(customFactory); // throws
// after
if (customFactory is UIElementFromSystemLibrary)
    viewModel.GroupInto(customFactory);
else
    logger.Warning("Grouping into user library panel types is not supported.");

if (!(factory is UIElementFromSystemLibrary sys) || !typeof(Panel).IsAssignableFrom(sys.Type)) return; // unsupported grouping target

bool CanGroupInto(IUIElementFactory factory) => factory is UIElementFromSystemLibrary sys && typeof(Panel).IsAssignableFrom(sys.Type);

try { viewModel.GroupInto(factory); }
catch (NotSupportedException ex) when (ex.Message.Contains("user library type")) {
    // notify user: grouping supports built-in panel types only
}

When it happens

Trigger: Executing 'group into' with an IUIElementFactory that is not UIElementFromSystemLibrary — e.g. grouping selected elements into a user-defined panel type from a custom library via the editor's group command.

Common situations: Users with custom UI element libraries selecting elements and choosing 'group into <custom panel>'; editor extensions exposing all factories to the grouping command.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Changing the panel from a user library type is currently…
• The given parentId does not correspond to any existing part.
• The control corresponding to the given parentId is a…
• The given assetSidePart.Id does not correspond to any…
• The given element is not a child of this panel.

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/c21b72de6f7a8459. Report an issue: GitHub.

Appendix: source

Thrown at sources/editor/Stride.Assets.Presentation/AssetEditors/UIEditor/ViewModels/UIEditorBaseViewModel.cs:592

            CreateAssetFromSelectedParts(() => new UIPageAsset { Design = new UIAssetBase.UIDesign { Resolution = UIAsset.Design.Resolution } }, e => e?.Name ?? "UIPage", false, out idRemappings);
        }

        /// <summary>
        /// Retrieves an enumeration of elements at the given UI-space position.
        /// </summary>
        /// <param name="worldPosition"></param>
        /// <returns></returns>
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        private IEnumerable<UIElementViewModel> GetElementsAtPosition(ref Vector3 worldPosition)
        {
            return Controller.AdornerService.GetElementIdsAtPosition(ref worldPosition).Select(id => FindPartViewModel(new AbsoluteId(Asset.Id, id))).OfType<UIElementViewModel>();
        }

        private void GroupInto(IUIElementFactory factory)
        {
            var targetPanelType = (factory as UIElementFromSystemLibrary)?.Type;
            if (targetPanelType == null)
                throw new NotSupportedException("Grouping elements into a user library type isn't supported.");
            if (!typeof(Panel).IsAssignableFrom(targetPanelType))
                throw new ArgumentException(@"The target type isn't a panel", nameof(targetPanelType));

            if (SelectedContent.Count == 0)
                return;

            // Ensure that the selected elements are sibling.
            var allParents = SelectedItems.Select(x => x.Parent).OfType<UIHierarchyItemViewModel>().ToList();
            var parent = allParents[0];
            if (allParents.Any(x => x != parent))
                throw new InvalidOperationException("This operation can only be executed on a selection of sibling elements.");

            using (var transaction = UndoRedoService.CreateTransaction())
            {
                var children = SelectedItems.ToList();
                // Create the new panel into which we'll insert the selection
                var newPanel = (Panel)Activator.CreateInstance(targetPanelType);
                var newPanelDesign = new UIElementDesign(newPanel);

View on GitHub (pinned to 96fad776d2)