[9fans] draw rpcs: 'o' and 'b' rectangles, on-screen, relative coordinates for screenimage

[9fans] draw rpcs: 'o' and 'b' rectangles, on-screen, relative coordinates for screenimage

[hiro]

I've been working on some abstraction for attach/detach support in draw(3).

To summarize the implementation: this entails mostly syncing draw(3)
state from two different instances, one of which being the one from
vncs, the other any terminal or drawterm (instead of running rio you
run some script that attaches to the devdraw replicator in vncs).

As all coordinates are by default absolute, right now i only see a way
to have my program be the only client to draw(3), once i were to run
it inside a rio window (like a subrio), the rio window would need to
be in 0,0 coordinates.

I have tried to put offsets into the rect in the 'o' rpc on all
allocated images that have pointers to screenimage, because what i
would really need is relative coordinates.
i also tried to just give different rect or cliprects to an
allocateimage 'b' rpc.
But this results in weird image corruption: after some graphics
operations, random parts of the images are either covered by black or
white areas, or even some weird other stuff looking like some kind of
random memory regions.

Is it supported to set offsets onto the rect in b and o rpc,
specifically targeting screenimage? or are these features that have
never been finished?

It's kinda hard to debug, so I would be very happy to get some higher
level guidence.