I am trying to create a form that will pop up over the top of a facebook page (not profile) when a user clicks onto that page, if the owner of the page has a specific app installed.
The popup would require the user to dismiss the popup/complete the form before they could interact with the page.
Apparently this used to be possible, does anyone know how to go about doing this now?
I suspect what I am after is a custom dialog that can be triggered on page load. Is such a thing possible in facebook?
This will not be possible. Facebook Pages no longer have what were called “Default Landing tabs” which would direct non-fan users to a particular tab app. Even then, this kind of popup behaviour would probably have been undesirable for users, possibly prohibited by Platform policy and likely blocked by most users browsers.
You can still create a Page tab app that can be gated behind any kind of restriction that you wish, however the regular Page content will still be visible to any user.