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Editor Utility Widget Subsystem

Base:
UEditorSubsystem
Type:
UNEditorUtilityWidgetSubsystem
Header File:
NexusUIEditor/Public/NEditorUtilityWidgetSubsystem.h

A UEditorSubsystem that stores per-widget state (FNWidgetState bags) and widget-to-tab mappings across editor sessions. The state itself is persisted via UPROPERTY(config) into the NexusUserSettings config, so a UNEditorUtilityWidget can be torn down and re-spawned (or the editor restarted) with its prior state intact.

The subsystem also tracks which editor tab last hosted each widget so utility widgets can be re-opened into the same tab layout next session — the mapping is stored in FNWidgetTabIdentifiers and the state bags themselves in FNWidgetStateSnapshot.

What It Does​

  • Persists Widget State: Each widget identifies itself with a stable FName (typically UNEditorUtilityWidget::UniqueIdentifier); the subsystem keys an FNWidgetState bag against it and writes the lot to the NexusUserSettings config.
  • Tracks Live Instances: Widgets register themselves in NativeConstruct and unregister in NativeDestruct. The subsystem holds a transient TMap<FName, TObjectPtr<UNEditorUtilityWidget>> for currently-alive instances so it can push cached state back into them before they go live.
  • Restores Tab Placement: The widget-to-tab map lets editor utility widgets reopen into the same docked tab they were closed from.

Widget State API​

Add Widget State​

/**
 * Store a new FNWidgetState under Identifier; overwrites any existing entry.
 * @param Identifier   Stable widget key (typically UNEditorUtilityWidget::UniqueIdentifier).
 * @param WidgetState  Key-value bag to persist.
 */
void AddWidgetState(const FName& Identifier, const FNWidgetState& WidgetState);

Update Widget State​

/**
 * Replace the stored state for Identifier with WidgetState; logs a warning if the widget is unknown.
 */
void UpdateWidgetState(const FName& Identifier, const FNWidgetState& WidgetState);

Remove Widget State​

/** Discard the stored state associated with Identifier. */
void RemoveWidgetState(const FName& Identifier);

Has Widget State​

/** @return True when a state bag exists for Identifier. */
bool HasWidgetState(const FName& Identifier) const;

Get Widget State​

/**
 * Retrieve a reference to the stored state for Identifier.
 * @note Not bounds-checked; callers must ensure HasWidgetState first.
 */
FNWidgetState& GetWidgetState(const FName& Identifier);

Live Instance API​

Register Widget​

/**
 * Register a live widget instance with the subsystem so state can be pushed into it.
 * Keyed by Widget->GetUniqueIdentifier().
 */
void RegisterWidget(UNEditorUtilityWidget* Widget);

Unregister Widget​

/** Drop a previously-registered widget; safe to call with widgets that were never registered. */
void UnregisterWidget(const UNEditorUtilityWidget* Widget);

Get Widget​

/** @return The widget if currently alive and registered, nullptr otherwise. */
UNEditorUtilityWidget* GetWidget(const FName& Identifier);

Has Widget​

/** @return True when a widget with Identifier is currently registered as live. */
bool HasWidget(const FName& Identifier);

Tab Identifier API​

Get Tab Identifier​

/**
 * Resolve the tab identifier most recently associated with WidgetIdentifier so the widget can
 * be re-spawned into the same tab on restore.
 * @return The associated tab identifier, or NAME_None if none is known.
 */
FName GetTabIdentifier(FName WidgetIdentifier);

Set Tab Identifier​

/** Record that a widget is currently hosted under TabIdentifier. */
void SetTabIdentifier(FName WidgetIdentifier, FName TabIdentifier);

Remove Tab Identifier​

/** Drop any tab-identifier mapping for WidgetIdentifier (e.g. when the user closes the tab permanently). */
void RemoveTabIdentifier(FName WidgetIdentifier);
warning

GetWidgetState is not bounds-checked — calling it with an unknown identifier asserts. Always guard with HasWidgetState first.