Manages undo history of scenes opened in the editor. [EditorUndoRedoManager] is a manager for [UndoRedo] objects associated with edited scenes. Each scene has its own undo history and [EditorUndoRedoManager] ensures that each action performed in the editor gets associated with a proper scene. For actions not related to scenes ([ProjectSettings] edits, external resources, etc.), a separate global history is used. The usage is mostly the same as [UndoRedo]. You create and commit actions and the manager automatically decides under-the-hood what scenes it belongs to. The scene is deduced based on the first operation in an action, using the object from the operation. The rules are as follows: - If the object is a [Node], use the currently edited scene; - If the object is a built-in resource, use the scene from its path; - If the object is external resource or anything else, use global history. This guessing can sometimes yield false results, so you can provide a custom context object when creating an action. Register a method that will be called when the action is committed (i.e. the "do" action). If this is the first operation, the [param object] will be used to deduce target undo history. Register a property value change for "do". If this is the first operation, the [param object] will be used to deduce target undo history. Register a reference for "do" that will be erased if the "do" history is lost. This is useful mostly for new nodes created for the "do" call. Do not use for resources. Register a method that will be called when the action is undone (i.e. the "undo" action). If this is the first operation, the [param object] will be used to deduce target undo history. Register a property value change for "undo". If this is the first operation, the [param object] will be used to deduce target undo history. Register a reference for "undo" that will be erased if the "undo" history is lost. This is useful mostly for nodes removed with the "do" call (not the "undo" call!). Commit the action. If [param execute] is true (default), all "do" methods/properties are called/set when this function is called. Create a new action. After this is called, do all your calls to [method add_do_method], [method add_undo_method], [method add_do_property], and [method add_undo_property], then commit the action with [method commit_action]. The way actions are merged is dictated by the [param merge_mode] argument. See [enum UndoRedo.MergeMode] for details. If [param custom_context] object is provided, it will be used for deducing target history (instead of using the first operation). Returns the [UndoRedo] object associated with the given history [param id]. [param id] above [code]0[/code] are mapped to the opened scene tabs (but it doesn't match their order). [param id] of [code]0[/code] or lower have special meaning (see [enum SpecialHistory]). Best used with [method get_object_history_id]. This method is only provided in case you need some more advanced methods of [UndoRedo] (but keep in mind that directly operating on the [UndoRedo] object might affect editor's stability). Returns the history ID deduced from the given [param object]. It can be used with [method get_history_undo_redo]. Returns [code]true[/code] if the [EditorUndoRedoManager] is currently committing the action, i.e. running its "do" method or property change (see [method commit_action]). Emitted when the list of actions in any history has changed, either when an action is committed or a history is cleared. Emitted when the version of any history has changed as a result of undo or redo call. Global history not associated with any scene, but with external resources etc. Invalid "null" history. It's a special value, not associated with any object.