umg-widgets

🧠 Brains complement: IF an unreal-engine-skills-manager tool (external MCP) exists in this session, call it with {action: "load", skill: "umg-and-slate"} for UE domain knowledge on this topic — correct APIs, architecture, best practices — and treat it as the rubric for any review / "best practices" question. If no such tool is available (e.g. running under Claude Code or Codex without that MCP), skip this line entirely and proceed with this skill alone — do NOT attempt the call.

UMG Widget Blueprints Skill

This skill covers authoring Widget Blueprints (WBP) with WidgetService. Read the Critical Rules below first — they prevent the most common failures. Then pick a task from the Task Index and load the matching workflow doc and/or run the matching sample script.

Load the blueprints skill when you also need to add Blueprint variables, functions, or components, and blueprint-graphs when wiring event-graph nodes for bound events.

Critical Rules

🚨 Creating Widget Blueprints — only one pattern works

WidgetService does not create the asset. Create it with the factory, then use WidgetService to populate it:

import unreal
factory = unreal.WidgetBlueprintFactory()
factory.set_editor_property("parent_class", unreal.UserWidget)
asset_tools = unreal.AssetToolsHelpers.get_asset_tools()
asset_tools.create_asset("MainMenu", "/Game/UI", unreal.WidgetBlueprint, factory)

Do not call BlueprintEditorLibrary.get_blueprint_class(), unreal.create_widget_blueprint(), or WidgetService.create_widget() — none exist. (Runnable: scripts/create_widget.txt.)

🚨 Hierarchy: set the root first, parents before children

unreal.WidgetService.add_component(path, "CanvasPanel", "RootCanvas", "", True)   # empty parent -> becomes root
unreal.WidgetService.add_component(path, "Button", "PlayButton", "RootCanvas", False)

That 5th argument is is_variable, not set_as_root — a widget becomes the root because its parent name is empty, not because of that flag. A 6th argument, child_index, inserts at a position instead of appending; reorder_component moves an existing widget within its parent. See reference.md ▸ Child order.