[AD] Why multiple windows might suck

[Peter Wang <tjaden@xxxxxxxxxx>]

(... or, "Doing more by doing less")

I'm thinking Allegro shouldn't try to support multiple windows
natively.

Rationale:

1. Multiple windows showing only Allegro BITMAPs are relatively
   useless, compared to attaching Allegro to GUI toolkits (GTK and the
   like).  I don't think many people will have a use for multiple
   plain BITMAP windows.

2. I think it would complicate the input system a lot.  I can't see
   asynchronously updated globals working well with multiple windows.
   (See Eric's rationale for not polling.)  It would probably also
   complicate other things (e.g. the GUI system, if it remains).

3. The common case is likely going to remain single monitor, single
   keyboard, single mouse, [etc], full screen games.  I think Allegro
   should be easy to use in the most common case, like it is now.

4. Other libraries have the multiple window environment figured out.
   We should leverage that work.

5. It's less work :-) 

I don't mean to say that we should just keep everything as-is, but
rather I think we should find ways to make Allegro cooperate with
other libraries better (e.g. more modular), and also expose some more
low-level stuff --- enough to build addons to interface *nicely* with
other libraries.  I think the Windows port does this well, but not the
X port.


PS. If you know Lua, I'm stealing their "meta-mechanisms" philosophy.

PPS. Eventually someone might even build a multi-platform addon that
interfaces with whichever toolkit is native on whatever OS.  Or just
interface with wxWindows, which has already done the hard work.