Client display configuration notification

[Alan Griffiths]

On 20/10/15 13:16, Gerry Boland wrote:
> - Is it in Mir's scope as a display server to provide a client api for configuring mir server settings like those for displays & input devices? Or should Mir expose a mirserver API for these settings, and require the shell to implement its own API via an alternative channel (e.g. DBus) for a settings client to use?

When asking a question like this it is important to consider what such
an API means in the context of a system Mir and (possibly multiple)
session Mir.

We currently provide both a client and server APIs for configuring
displays - and (ignoring a mass of bugs) the display config set by the
active session Mir is applied by the system Mir. And the display config
set by the current client is applied to the session Mir and recursively
to the system Mir.

That model makes sense to me. (Although as discussed in this thread the
current implementation of that model is somewhat lacking.)

I don't think there's a need for an API to change the "base"
configuration of the system Mir which suggests that such an API might
not be core to Mir. OTOH it isn't a costly thing to provide or support.