src/vs/editor/contrib/gotoSymbol/browser/symbolNavigation.ts/EditorState/_onDidAddEditor
class EditorState:	private _onDidAddEditor(editor: ICodeEditor): void {
		this._listener.set(editor, combinedDisposable(
			editor.onDidChangeCursorPosition(_ => this._onDidChange.fire({ editor })),
			editor.onDidChangeModelContent(_ => this._onDidChange.fire({ editor })),
		));
	}