I have an XML layout file, specifically
customer_account_login.xml, which is processed automatically by Magento and replaces the out-of-the-box copy.
In some cases I would like to do this, while in others I want the out-of-the-box file (based on backend configuration).
I have not found a way to turn off processing for my XML file under certain conditions, but assume there is some class that can be overridden to do this. A generic way would be preferable, but I could live with a method that toggles just this specific XML file.
To clarify: the question is about avoiding processing the XML file entirely, not how to conditionally show/hide certain blocks and other layout elements.