Ada & MacOS

[sg <alpha@skynet.org.pl_WITHOUT>]

Hi,
I'm going to develop a small (later it will be bigger as further modules 
come up) application for small business. It is going to work under 
windows, linux and macos having very similar GUI and using common 
database (it will be PostgreSQL). I wanted to use 
C++/wxWindows/PostgreSQL for that but I'd rather go in the Ada 
direction, so I've got some questions:

1. Is it possible to such a program in Ada with as less work as possible 
while creating GUT for another OS ? I wanted to develop it under 
windows, and then try to run it under MacOS without too much work, I 
want to avoid the situation when I have to create another another GUI 
from the beginning.

2. Is there any compiler for Ada under MacOS that is compatible with a 
compiler for Linux and Windows.

3. Does anybody have any experience with using PostgreSQL with Ada on 
all of theese systems (or maybe choose another database) ?

4. How about prining with gtkAda ?

regards
Szymon Guz