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Re: AppIcon patch revisited

From: Richard Frith-Macdonald
Subject: Re: AppIcon patch revisited
Date: Sat, 10 Feb 2001 08:17:59 +0000

On Saturday, February 10, 2001, at 07:43 AM, Dan Pascu wrote:

> On  9 Feb, Richard Frith-Macdonald wrote: 
> >> Relaying the left click to wmaker allows wmaker to move the appicon  
> >> around.  
> >  
> > If the backend gives the left mouse click to Window Maker, then the 
> > app (ie the code written using the OpenStep API) doesn't get it, and 
> Of course it does. Relaying doesn't mean that you completely give away 
> the event. you receive the event, process as you need, then duplicate 
> it (send a copy of it) to wmaker. So _both_ your app and wmaker get the 
> event (if you decide the events needs to be relayed to wmaker). 
> You can pass it to your app to do whatever it needs with it, then if 
> necessary send a copy to wmaker too. 

Of course, the above is nonsense in the context of a GNUstep app ...
if you have both Window Maker and the GNUstep app (OpenStep API code)\
trying to deal with the same event then you get total confusion.

I think you are suggesting this because you still don't understand the
nature of the system ... I've tried to explain a few times, and I'll try
again ... but perhaps you need to resort to looking at the code?

The GNUstep application consists of three separate layers ...

1. The application proper, written by some developer using the OpenStep
API (plus MacOS-X and GNUstep specific extensions perhaps).
Code at this level operates purely with the OpenStep/GNUstep API

2. The GNUstep gui (frontend) library ... a collection of objects that provide 
API that the developer uses to write the application.
Code at this level operates purely with the system independant API to the
backend library.

3. The GNUstep xgps (backend) library (or xdps library, or in future perhaps 
non-X libraries).  This library is the only part of the code that even knows 
X exists.  It handles all the interface with the X system and the window 

Just to stress a point ... each layer communicates with the other layers by a 
defined API, and *no* knowledge of X exists in the top two layers.

So, when an X event arrives, the xgps library converts it to an OpenStep event
and inserts it into the event queue in the gui library.  The gui library then
presents it to the application code, and the application code decides what
action to perform in response to the event.

There is obviously no way for the application code at the top level to know if
the bottom level xgps code has forwarded a copy of an event to the X window
manager - nor should a developer working at the top layer *need* to know
anything about what is going on in the bottom X-windows layer.

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