wl_output physical size when unknown

[David Edmundson]

I need to patch either a client toolkit or a compositor and I'm not sure which.

There are some cases where we don't have a physical size for an output.
For example projectors or headless virtual machines,

Currently we (kwin) can send a physical size of 0,0 which is causing
some client issues which are calculating us as having 0 dots per inch
and doing something wrong.

Should:
 a) Compositors should generate something fake but sensible
 b) Clients should handle this case

I think there's a strong argument for either. What are others doing?

David