Code review comment for lp:~alan-griffiths/mir/fix-1516670

> Are the visual artifacts on phone/desktop/both?

Both, but easier to see on phone.

> And what are the cases where outputs overlap?

When displays of different sizes are "cloned".

So, with an external monitor attached to a mako:

$ sudo stop lightdm
$ bin/mir_demo_server --window-manager system-compositor&
$ bin/mir_demo_standalone_render_surfaces --no-file --host $XDG_RUNTIME_DIR/mir_socket --display-config clone

On the external monitor the fullscreen for the phone output is overlayed[1] on top of the fullscreen for the external monitor and the edge is visible as the flying surfaces it (as the rendering is not quite in sync.)

> We could also potentially run into max texture size issues for high res
> displays if we attempt to do 1.2.

Yep.

> In any case, a fullscreen surface per output makes sense to me.

[1] I'm not sure if this ordering is guaranteed, but was consistent in my limited testing.