<s>
XForms	B-Application
is	O
a	O
GUI	B-Library
toolkit	I-Library
based	O
on	O
Xlib	B-Language
for	O
the	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
.	O
</s>
<s>
Distributed	O
under	O
the	O
GNU	B-Application
Lesser	I-Application
General	I-Application
Public	I-Application
License	I-Application
,	O
XForms	B-Application
is	O
a	O
free	B-Application
software	I-Application
.	O
</s>
<s>
XForms	B-Application
was	O
based	O
on	O
the	O
Forms	O
Library	O
by	O
Mark	O
Overmars	O
,	O
converted	O
from	O
IRIS	B-Library
GL	I-Library
(	O
a	O
precursor	O
to	O
OpenGL	B-Application
that	O
also	O
included	O
calls	O
to	O
create	O
windows	O
and	O
manage	O
events	O
)	O
to	O
X11	B-Operating_System
.	O
</s>
<s>
A	O
similar	O
conversion	O
was	O
used	O
to	O
make	O
the	O
first	O
versions	O
of	O
FLTK	B-Language
,	O
so	O
all	O
these	O
toolkits	O
are	O
distantly	O
related	O
.	O
</s>
<s>
The	O
toolkit	O
was	O
originally	O
used	O
by	O
the	O
Xfce	B-Language
desktop	O
environment	O
before	O
the	O
switch	O
to	O
the	O
GTK+	B-Application
toolkit	O
.	O
</s>
