Use this skill when working with UMG, UI, widget, UserWidget, Slate, HUD, BindWidget, Common UI, menu, or UMG binding in Unreal Engine. See references/widget-types.md for widget type reference and references/common-ui-setup.md for Common UI plugin setup. For Slate in editor tools, see ue-editor-tool

UE UI: UMG, Slate, and Common UI You are an expert in Unreal Engine's UI systems (UMG, Slate, and Common UI). Context Check Read .agents/ue project context.md to determine: which UI plugins are enabled (CommonUI, MVVM), target platforms (affects input method), whether this is multiplayer (widget ownership per player), and existing UI base class conventions. Information Gathering Before writing UI code, confirm: UI type (HUD, full screen menu, modal, in world WidgetComponent), input requirements (mouse, gamepad, keyboard), target platforms, and widget lifecycle (persistent, transient, or pooled). 1. UUserWidget in C++ Lifecycle and GC 2. BindWidget Pattern Name must match the UMG Blueprint widget name exactly (case sensitive). Always null check optional bindings. 3. Widget Interaction UButton (Button.h) UTextBlock (TextBlock.h) UImage (Image.h) UProgressBar (ProgressBar.h) UScrollBox (ScrollBox.h) UScrollBox is a BindWidget compatible container for scrollable content. Supports vertical and horizontal scroll. Add child widgets in Blueprint; query or modify scroll offset in C++: UListView + UTileView + IUserObjectListEntry (ListView.h, TileView.h, IUserObjectListEntry.h) UListView — virtualised vertical list. UTileView — same interface, displays items in a grid layout (set tile width/height in the widget Designer panel). Both use IUserObjectListEntry . 4. Input Mode Management Set input mode from calling code (HUD/GameMode) after AddToViewport , not from NativeConstruct . 5. Common UI (Plugin) See references/common ui setup.md for full plugin setup, GameViewportClient config, and layer architecture. Enable CommonUI and CommonInput plugins. Set viewport client to UCommonGameViewportClient in Project Settings Maps & Modes Game Viewport Client Class. UCommonGameViewportClient detects input method changes (gamepad vs mouse vs touch) and broadcasts them via UCommonInputSubsystem — this drives automatic gamepad/keyboard navigation and button prompt switching. UCommonActivatableWidget (CommonActivatableWidget.h) Widget Containers (CommonActivatableWidgetContainerBase.h) UCommonActivatableWidgetContainerBase is the base class for Common UI widget containers. Two concrete subclasses: UCommonActivatableWidgetStack — shows only the topmost widget; deactivating reveals the previous one (stack behaviour). This is the correct stack class — do NOT use UCommonActivatableWidgetSwitcher here, which inherits from UCommonAnimatedSwitcher / UWidgetSwitcher and is a different widget entirely. UCommonActivatableWidgetQueue — FIFO queue; displays widgets sequentially, advancing to the next when the current deactivates. UCommonButtonBase Uses FCommonButtonEvent (declared via DECLARE EVENT ) — use AddUObject , not AddDynamic : UCommonUIActionRouter Handles input routing between game and UI layers; Common UI drives it automatically via GetDesiredInputConfig . Access directly when you need to query the current input mode: Gamepad / Keyboard Navigation Common UI provides automatic gamepad and keyboard navigation without extra setup. Key behaviours: UCommonButtonBase highlights automatically when it receives focus via D pad or Tab navigation. UCommonActivatableWidget::NativeGetDesiredFocusTarget() controls which widget receives focus when the screen activates. When a widget deactivates, Common UI restores focus to the widget that was active before it opened — no manual focus bookkeeping required. Bind GetDesiredInputConfig to ECommonInputMode::Menu to suppress game input while a menu is open. 6. Slate Fundamentals Use Slate for editor extensions, custom renderers, or when UMG doesn't expose required functionality. SWidget is the abstract base of all Slate widgets. SCompoundWidget (shown below) is the typical subclass for custom widgets. Common Slate widgets: STextBlock , SButton , SVerticalBox , SHorizontalBox , SOverlay , SBorder , SBox , SScrollBox , SImage , SEditableTextBox . Slate vs UMG: Use Slate for editor tools and maximum control. Use UMG for game runtime UI, Blueprint extensibility, animations, and BindWidget. 7. MVVM (UE 5.1+, ModelViewViewModel plugin) To bind a ViewModel at runtime: create with NewObject<UMyGameViewModel (this) , then configure in the widget Blueprint's Bindings panel. The UMVVMView component on the widget handles one way and two way property bindings automatically once the ViewModel class is set. Common Mistakes Anti pattern Correct approach SetVisibility(Hidden) to "hide" a menu RemoveFromParent() to stop rendering and input CreateWidget(GetWorld(), ...) for HUD widgets CreateWidget(GetOwningPlayer(), ...) SetInputMode(FInputModeUIOnly()) for a HUD Use FInputModeGameAndUI or Common UI's GetDesiredInputConfig AddDynamic with UCommonButtonBase::OnClicked() AddUObject — it's FCommonButtonEvent not DYNAMIC Binding delegates in NativeTick Bind once in NativeConstruct , unbind in NativeDestruct Skipping Super::NativeOnActivated/Deactivated Always call Super — it routes focus and input One widget for all players in split screen AddToPlayerScreen with per player widgets No UPROPERTY reference after RemoveFromParent (widget leak) Hold a UPROPERTY() TObjectPtr< to prevent GC, or call RemoveFromParent() to allow GC when no longer needed Z order conflicts Multiple widgets at same Z order causes undefined draw order Use explicit Z order in AddToViewport(ZOrder) — higher values draw on top. Reserve ranges: HUD 0 9, menus 10 19, popups 20+ Invisible widgets still tick Hidden widgets with NativeTick consume CPU Set SetVisibility(ESlateVisibility::Collapsed) (removes from layout) or call RemoveFromParent() for unused widgets. Override NativeTick with an early out: if (!IsVisible()) return; Build.cs Related Skills ue cpp foundations — UPROPERTY meta specifiers, TObjectPtr, module setup ue input system — Enhanced Input, FInputModeXxx, input contexts ue editor tools — Slate for editor detail panels and custom tools

ue-ui-umg-slate