In the angular-editor library, it is straightforward to get the inEditor and inEditorPreview statuses via a fiunction call.

In the react-editor library it is not available from the hosting app. Please change the react-editor library to make this a simple function call as in the angular library.

Workaround - reimplemnt the window and mgnlRefresh checking in your own app.

Reason

Apps need to know if they are running in the context of the Page editor BEFORE they instantiate a <Page> component - because they need to decide whether to load the tempalateDefinition REST endpoint or not.