Overview of IUP?

[Duck <duck@...>]

I downloaded and naively tried to compile IUP 2.6 on Linux. I very quickly 
ran out of luck, like this:

 $ make
 ==== Building iup ====
 ==== Building iup ====
 icalcsize.c
 icall.c
 [. . .]
 mothelp.c
 motif.c
 In file included from /usr/include/Xm/XmP.h:29,
                  from /usr/include/Xm/Print.h:29,
                  from mot/motif.c:784:
 /usr/include/X11/IntrinsicP.h:301: error: conflicting types for 
 'XtMoveWidget'
 mot/motif.c:38: error: previous declaration of 'XtMoveWidget' was here
 make[2]: *** [../obj/iup/Debug/motif.o] Error 1
 make[1]: *** [iup] Error 2
 make: *** [iup] Error 2

This led me to look into the whole IUP think a bit more closely, and to 
come up with the following questions:

1. The website mentions GTK-2 support, but there isn't any. Apparently 
that's in V3, which isn't out yet. Any idea when it will be? (I'm not 
really interested in a Motif look-and-feel if I can have a GTK one.)

2. Can the IUP libraries be used directly from Lua by simply doing a 
require() of the right modules and then coding 100% in Lua?

3. In the interim, any ideas on what to do about the above build error?