<s>
Tweak	B-Application
is	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
(	O
GUI	B-Application
)	O
layer	O
written	O
by	O
Andreas	B-Operating_System
Raab	I-Operating_System
for	O
the	O
Squeak	B-Operating_System
development	O
environment	O
,	O
which	O
in	O
turn	O
is	O
an	O
integrated	B-Application
development	I-Application
environment	I-Application
based	O
on	O
the	O
Smalltalk-80	B-Application
computer	O
programming	O
language	O
.	O
</s>
<s>
Tweak	B-Application
is	O
an	O
alternative	O
to	O
an	O
earlier	O
graphic	B-Application
user	I-Application
interface	I-Application
layer	O
called	O
Morphic	O
.	O
</s>
<s>
Applications	O
that	O
use	O
the	O
Tweak	B-Application
software	O
include	O
Sophie	O
(	O
version	O
1	O
)	O
,	O
a	O
multimedia	O
and	O
e-book	O
authoring	O
system	O
,	O
and	O
a	O
family	O
of	O
virtual	O
world	O
systems	O
:	O
Open	B-Protocol
Cobalt	I-Protocol
,	O
Teleplace	O
,	O
OpenQwaq	B-Application
,	O
3d	O
ICC	O
's	O
Immersive	O
Terf	O
and	O
the	O
Croquet	B-Protocol
Project	I-Protocol
.	O
</s>
<s>
An	O
experimental	O
version	O
of	O
Etoys	B-Application
,	O
a	O
programming	B-Application
environment	I-Application
for	O
children	O
,	O
used	O
Tweak	B-Application
instead	O
of	O
Morphic	O
.	O
</s>
<s>
Etoys	B-Application
was	O
a	O
major	O
influence	O
on	O
a	O
similar	O
Squeak-based	O
programming	B-Application
environment	I-Application
known	O
as	O
Scratch	B-Language
.	O
</s>
