<s>
The	O
IUP	B-Language
Portable	O
User	O
Interface	O
is	O
a	O
computer	O
software	B-Application
development	I-Application
kit	I-Application
that	O
provides	O
a	O
portable	O
,	O
scriptable	O
toolkit	O
to	O
build	O
graphical	B-Application
user	I-Application
interfaces	I-Application
(	O
GUIs	B-Application
)	O
using	O
the	O
programming	O
languages	O
C	B-Language
,	O
Perl	B-Language
,	O
Lua	B-Language
,	O
Nim	B-Application
and	O
Zig	B-Application
,	O
among	O
others	O
.	O
</s>
<s>
This	O
allows	O
rapid	O
,	O
zero-compile	O
prototyping	O
and	O
refinement	O
of	O
deployable	O
GUI	B-Application
applications	O
.	O
</s>
<s>
IUP	B-Language
's	O
purpose	O
is	O
to	O
allow	O
programs	O
user	O
interface	O
to	O
run	O
in	O
different	O
systems	O
in	O
unmodified	O
form	O
.	O
</s>
<s>
It	O
provides	O
this	O
ability	O
by	O
binding	B-Application
Lua	B-Language
with	O
its	O
C/C	O
++	O
code	O
,	O
or	O
simply	O
writing	O
C	B-Language
to	O
the	O
application	B-Application
programming	I-Application
interface	I-Application
(	O
API	B-Application
)	O
.	O
</s>
<s>
It	O
handles	O
user	O
interface	O
elements	O
by	O
using	O
native	O
controls	O
provided	O
by	O
native	O
APIs	B-Application
,	O
such	O
as	O
Windows	B-Library
API	I-Library
in	O
Windows	B-Application
,	O
GTK+	B-Application
in	O
Linux	B-Application
,	O
and	O
Motif-LessTif	O
in	O
older	O
Unices	O
.	O
</s>
<s>
It	O
also	O
provides	O
some	O
custom	O
developed	O
controls	O
using	O
graphics	O
APIs	B-Application
such	O
as	O
CD	O
-	O
Canvas	O
Draw	O
or	O
OpenGL	B-Application
.	O
</s>
<s>
IUP	B-Language
's	O
distinguishing	O
features	O
include	O
:	O
</s>
<s>
ANSI	O
C	B-Language
API	B-Application
,	O
one	O
of	O
the	O
few	O
plain	O
C-capable	O
toolkits	O
,	O
</s>
<s>
Single	O
API	B-Application
for	O
Windows	B-Application
or	O
Linux	B-Application
,	O
</s>
<s>
Built	O
in	O
support	O
for	O
Lua	B-Language
scripts	I-Language
calling	O
IUP	B-Language
functions	B-Language
(	O
controlled	O
by	O
Lua	B-Language
script	I-Language
)	O
,	O
</s>
<s>
Removal	O
of	O
the	O
restriction	O
of	O
class/instance	O
object	B-Language
types	O
,	O
but	O
retaining	O
the	O
prototype	B-Application
Lua-style	O
hierarchy	O
of	O
inheritance	O
.	O
</s>
<s>
An	O
abstract	B-Application
layout	O
model	O
,	O
in	O
which	O
sizes	O
and	O
positions	O
are	O
calculated	O
from	O
horizontal	O
and	O
vertical	O
containers	O
,	O
rather	O
than	O
explicit	O
X	O
and	O
Y	O
coordinates	O
.	O
</s>
<s>
Small	O
API	B-Application
,	O
on	O
the	O
order	O
of	O
about	O
100	O
functions	B-Language
.	O
</s>
<s>
This	O
main	B-General_Concept
loop	I-General_Concept
can	O
be	O
called	O
inside	O
Lua	B-Language
.	O
</s>
<s>
This	O
is	O
the	O
reverse	O
of	O
the	O
usual	O
situation	O
for	O
assembling	O
GUI	B-Application
elements	O
.	O
</s>
<s>
The	O
Lua	B-Language
scripting	I-Language
is	O
done	O
by	O
binding	B-Application
Lua	B-Language
and	O
IUPLua	O
in	O
(	O
at	O
least	O
)	O
a	O
small	O
C	B-Language
program	I-Language
called	O
a	O
host	O
application	O
.	O
</s>
<s>
This	O
program	O
creates	O
a	O
Lua	B-Language
state	O
,	O
passes	O
the	O
Lua	B-Language
state	O
to	O
IUPLua	O
for	O
initialization	O
,	O
and	O
then	O
opens	O
and	O
executes	O
a	O
Lua	B-Language
script	I-Language
against	O
the	O
Lua	B-Language
state	O
.	O
</s>
<s>
Or	O
,	O
the	O
entire	O
IUP	B-Language
state	O
can	O
be	O
dynamically	O
loaded	O
via	O
use	O
of	O
a	O
Lua	B-Language
require	O
or	O
package.loadlib	O
of	O
IUPLua	O
.	O
</s>
<s>
The	O
script(s )	O
can	O
later	O
be	O
compiled	O
with	O
the	O
Lua	B-Language
compiler	O
if	O
needed	O
.	O
</s>
<s>
Support	O
for	O
UTF-8	O
was	O
added	O
to	O
the	O
Windows	B-Application
target	O
in	O
November	O
2013	O
with	O
the	O
release	O
of	O
version	O
3.9	O
.	O
</s>
<s>
IUP	B-Language
is	O
liberally-licensed	O
for	O
free	O
use	O
,	O
modification	O
,	O
sale	O
,	O
and	O
redistribution	O
under	O
the	B-License
MIT	I-License
license	I-License
.	O
</s>
<s>
IUP	B-Language
has	O
been	O
in	O
development	O
at	O
least	O
since	O
the	O
1.8	O
version	O
issued	O
in	O
1998	O
.	O
</s>
