<s>
was	O
the	O
default	O
window	B-Application
manager	I-Application
used	O
by	O
the	O
GNOME	B-Language
2	I-Language
desktop	O
environment	O
until	O
it	O
was	O
replaced	O
by	O
Mutter	B-Language
in	O
GNOME	B-Application
3	O
.	O
</s>
<s>
It	O
is	O
still	O
used	O
by	O
GNOME	B-Application
Flashback	O
,	O
a	O
session	O
for	O
GNOME	B-Application
3	O
that	O
provides	O
a	O
similar	O
user	O
experience	O
to	O
the	O
Gnome	B-Application
2.x	O
series	O
sessions	O
.	O
</s>
<s>
The	O
development	O
of	O
Metacity	B-Language
was	O
started	O
by	O
Havoc	O
Pennington	O
and	O
it	O
was	O
released	O
under	O
the	O
GNU	B-License
General	I-License
Public	I-License
License	I-License
.	O
</s>
<s>
Before	O
the	O
introduction	O
of	O
Metacity	B-Language
in	O
GNOME	B-Application
2.2	O
,	O
GNOME	B-Application
used	O
Enlightenment	B-Application
and	O
then	O
Sawfish	B-Language
as	O
its	O
window	B-Application
manager	I-Application
.	O
</s>
<s>
Although	O
Metacity	B-Language
was	O
designed	O
to	O
integrate	O
into	O
the	O
GNOME	B-Application
desktop	I-Application
,	O
it	O
does	O
not	O
require	O
it	O
to	O
run	O
,	O
while	O
GNOME	B-Application
can	O
be	O
used	O
with	O
different	O
window	B-Application
managers	I-Application
provided	O
that	O
they	O
support	O
the	O
part	O
of	O
the	O
ICCCM	B-Operating_System
specification	O
that	O
GNOME	B-Application
requires	O
.	O
</s>
<s>
Metacity	B-Language
uses	O
the	O
GTK	B-Application
graphical	B-Library
widget	I-Library
toolkit	I-Library
to	O
create	O
its	O
user	O
interface	O
components	O
,	O
which	O
makes	O
it	O
themeable	O
and	O
makes	O
it	O
blend	O
in	O
with	O
other	O
GTK	B-Application
applications	O
.	O
</s>
<s>
Originally	O
,	O
Metacity	B-Language
used	O
GTK	B-Application
2	O
however	O
as	O
of	O
version	O
3.12.0	O
it	O
has	O
been	O
ported	O
to	O
GTK	B-Application
3	O
.	O
</s>
<s>
Metacity	B-Language
's	O
focus	O
is	O
on	O
simplicity	O
and	O
usability	O
rather	O
than	O
novelties	O
.	O
</s>
<s>
Its	O
author	O
has	O
characterized	O
it	O
as	O
a	O
"	O
Boring	O
window	B-Application
manager	I-Application
for	O
the	O
adult	O
in	O
you	O
.	O
</s>
<s>
Many	O
window	B-Application
managers	I-Application
are	O
like	O
Marshmallow	O
Froot	O
Loops	O
;	O
Metacity	B-Language
is	O
like	O
Cheerios.	O
"	O
</s>
<s>
People	O
in	O
favour	O
of	O
Metacity	B-Language
say	O
that	O
it	O
is	O
aimed	O
at	O
new	O
computer	O
users	O
who	O
do	O
not	O
need	O
the	O
abundant	O
options	O
and	O
functionality	O
of	O
Sawfish	B-Language
or	O
Enlightenment	B-Application
.	O
</s>
<s>
Havoc	O
Pennington	O
wrote	O
an	O
essay	O
explaining	O
why	O
he	O
wrote	O
Metacity	B-Language
and	O
simplified	O
the	O
GNOME	B-Application
desktop	I-Application
.	O
</s>
<s>
Despite	O
the	O
incomplete	O
state	O
of	O
Metacity	B-Language
theme	O
development	O
documentation	O
,	O
many	O
themes	O
have	O
been	O
written	O
for	O
Metacity	B-Language
.	O
</s>
<s>
A	O
popular	O
theme	O
engine	O
is	O
Clearlooks	B-Application
,	O
which	O
was	O
the	O
default	O
in	O
GNOME	B-Application
from	O
version	O
2.12	O
until	O
the	O
release	O
of	O
GNOME	B-Application
3	O
and	O
GNOME	B-Application
Shell	O
.	O
</s>
