I think this is a misunderstanding of how screenshots work, and how Wayland has always intended to deal with the issue.
First of all, note that as with any window system, application buffers are not the final version of what you see on the screen. A normal desktop has wallpapers, transparency, task bars, multiple windows and window occlusion.
This means that apart from a few special cases, only the compositor knows how the full scene currently looks, and is the only entity capable of producing a buffer containing the entire thing.
For this reason, the only way to do screenshots is to have a way to ask the compositor for one. This is the case for any windowing system, and nothing related to buffer management will change that.
> ... that they didn't include a security policy mechanism for coordinating Wayland buffers
Depending on what you mean, this is either slightly or very untrue. Basically, when you try to present to screen, a client takes a buffer (which is private) and commits it to a surface. This temporarily borrows it to the server.
Should the server wish to share the buffer, this is when this would be done. Before doing so, the server would enforce any security restrictions as necessary. This is how all client-to-client communication happens in wayland: With the server as mediator, when it permits it.
A screenshot of a window or direct-scanout application could be implemented by simply having the server further borrow the buffer to a recording application, with appropriate restrictions in place.
> users really want applications to be able to snoop on each other when required.
I don't understand why you would think that this is a problem under Wayland. They only difference is that while X11 implicitly allows everyone to snoop on everything without any way to control it, snooping in Wayland is explicit, and servers can prompt users to permit it per application. Or not, it's up to the server.
First of all, note that as with any window system, application buffers are not the final version of what you see on the screen. A normal desktop has wallpapers, transparency, task bars, multiple windows and window occlusion.
This means that apart from a few special cases, only the compositor knows how the full scene currently looks, and is the only entity capable of producing a buffer containing the entire thing.
For this reason, the only way to do screenshots is to have a way to ask the compositor for one. This is the case for any windowing system, and nothing related to buffer management will change that.
> ... that they didn't include a security policy mechanism for coordinating Wayland buffers
Depending on what you mean, this is either slightly or very untrue. Basically, when you try to present to screen, a client takes a buffer (which is private) and commits it to a surface. This temporarily borrows it to the server.
Should the server wish to share the buffer, this is when this would be done. Before doing so, the server would enforce any security restrictions as necessary. This is how all client-to-client communication happens in wayland: With the server as mediator, when it permits it.
A screenshot of a window or direct-scanout application could be implemented by simply having the server further borrow the buffer to a recording application, with appropriate restrictions in place.
> users really want applications to be able to snoop on each other when required.
I don't understand why you would think that this is a problem under Wayland. They only difference is that while X11 implicitly allows everyone to snoop on everything without any way to control it, snooping in Wayland is explicit, and servers can prompt users to permit it per application. Or not, it's up to the server.