Present information to the user when there is missing support for some Annotations
From comment in issue #1296 (closed):
An error message inside the PDF-viewer would be nice - i have several times had to work with these and wondered why nothing showed up.
Perhaps we could use a info bar to display such information. However, we would need to assess how feasible is to get non-scary information from the backends, and the display it in the PDF itself without being a hassle.
So, filing the issue to evaluate it. It might or might not work.