[Xevie] Re: Invitation to a discussion about an External Event Manager

[Deron Johnson]

Keith Packard wrote:
 > Yes, it allows essentially the parallel semantics for Composite's output
 > redirection.  However, I'm not considering changing how grabs work; I 
don't
 > see a reason at this point to override the regular grab semantics.  It
 > would take quite a bit to convince me otherwise.

and also:

 > I'm not sure what kinds of control will be necessary; right now, all I
 > want is to be able to override the X/Y -> Window mapping within the X
 > server.

I don't see a need to change the grab semantics. However, it my
environment it is necessary to implement the grab semantics (according
to the normal X11 rules) in my redirection client (aka the Display
Server).  I need to do this because not only do I need to provide a
comparable grabbing mechanism for LG-aware clients (which the X server
doesn't know about) but I also need to ensure that X and LG-aware
client grabs intermix properly.  Also, the grab processing needs to
start after the initial event window is determined, and this isn't
known until after the Display Server does its pick operation.

Since grabbing processing is fully performed in my redirection client,
I would like the ability for the redirection client to specify to to
the X server that no further grab processing should be done on this
event, but to do only event propogation. This is the type of "control"
I'm talking about.

 > I envision your 'display manager' wanting to just consume events
 > directed at 3D windows and not hand them back to the X server.

My Display Server consumes events directed at LG-aware client windows
(what you call 3D windows); these never go back to the X server. But
if the hit window is an X window, the events will eventually go back
to the X server. But they will do so after grab processing has been
performed. If any non-null grab processing occurred, the event will
have been "fully resolved" and no further event propogation will be
necessary in the server. However, if no grab processing occurred for
this event, the Display Server will want event propogation to be
performed for the event.

 > If you see a reason for the redirecting client to need finer grain 
control
 > over event processing, please explain further.

Hopefully, my explanations above are clear. If they are not, perhaps
we can talk about it over the phone. Also, please review the draft
document I sent out. Hopefully this can explain my design rationale
further.