Define semantics of `wl_shm` with tiled or multi-plane formats
The semantics of wl_shm
with tiled or multi-plane formats are not clear. In particular, I am not aware of any document specifying how to handle sizes that are not a multiple of the subsampling quantum.
Edit:
- As per #333 (comment 1619508), tiled formats are never valid.
- Is the same true of formats that require a non-linear modifier?