XF 2.2 Is possible to detect inside a template or PHP, that was loaded as Overlay?

[Scandal]

How I could detect if a template is loaded as overlay?
I mean the pages

overlay="true"
data-xf-click="overlay"

via template or PHP code.

I scanned all /src/XF files but didn't find something as class method etc.

 

[Lukas W.]

The only check you can make in the backend is, if the page was requested via AJAX. There's no way to differentiate between an overlay, menu, tab or any other AJAX call. If you need specifically overlays, you'll need to extend the overlay trigger script to pass a custom parameter to the server.