<s>
XView	B-Library
is	O
a	O
widget	B-Library
toolkit	I-Library
from	O
Sun	O
Microsystems	O
introduced	O
in	O
1988	O
.	O
</s>
<s>
It	O
provides	O
an	O
OPEN	B-Operating_System
LOOK	I-Operating_System
user	O
interface	O
for	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
applications	O
,	O
with	O
an	O
object-oriented	O
application	B-Application
programming	I-Application
interface	I-Application
(	O
API	B-Application
)	O
for	O
the	O
C	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
Its	O
interface	O
,	O
controls	O
,	O
and	O
layouts	O
are	O
very	O
close	O
to	O
that	O
of	O
the	O
earlier	O
SunView	B-Library
window	O
system	O
,	O
making	O
it	O
easy	O
to	O
convert	O
existing	O
applications	O
from	O
SunView	B-Library
to	O
X	B-Operating_System
.	O
</s>
<s>
Sun	O
also	O
produced	O
the	O
User	B-Library
Interface	I-Library
Toolkit	I-Library
(	O
UIT	O
)	O
,	O
a	O
C++	B-Language
API	B-Application
to	O
XView	B-Library
.	O
</s>
<s>
The	O
XView	B-Library
source	O
code	O
has	O
been	O
freely	O
available	O
since	O
the	O
early	O
1990s	O
,	O
making	O
it	O
the	O
"	O
first	O
open-source	B-Application
professional-quality	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
toolkit	O
"	O
.	O
</s>
<s>
XView	B-Library
was	O
later	O
abandoned	O
by	O
Sun	O
in	O
favor	O
of	O
Motif	B-Application
(	O
the	O
basis	O
of	O
CDE	B-Application
)	O
,	O
and	O
more	O
recently	O
GTK+	B-Application
(	O
the	O
basis	O
of	O
GNOME	B-Application
)	O
.	O
</s>
<s>
XView	B-Library
was	O
reputedly	O
the	O
first	O
system	O
to	O
use	O
right-button	O
context	O
menus	O
,	O
which	O
are	O
now	O
ubiquitous	O
among	O
computer	O
user	O
interfaces	O
.	O
</s>
