<s>
In	O
user	B-Application
interface	I-Application
design	O
,	O
a	O
mode	O
is	O
a	O
distinct	O
setting	O
within	O
a	O
computer	B-Application
program	I-Application
or	O
any	O
physical	O
machine	O
interface	B-Application
,	O
in	O
which	O
the	O
same	O
user	B-General_Concept
input	I-General_Concept
will	O
produce	O
perceived	O
results	O
different	O
from	O
those	O
that	O
it	O
would	O
in	O
other	O
settings	O
.	O
</s>
<s>
Modal	O
interface	B-Application
components	O
include	O
the	O
Caps	B-Device
lock	I-Device
and	O
Insert	B-Device
keys	I-Device
on	O
the	O
standard	O
computer	B-Device
keyboard	I-Device
,	O
both	O
of	O
which	O
typically	O
put	O
the	O
user	O
's	O
typing	O
into	O
a	O
different	O
mode	O
after	O
being	O
pressed	O
,	O
then	O
return	O
it	O
to	O
the	O
regular	O
mode	O
after	O
being	O
re-pressed	O
.	O
</s>
<s>
An	O
interface	B-Application
that	O
uses	O
no	O
modes	O
is	O
known	O
as	O
a	O
modeless	B-General_Concept
interface	B-Application
.	O
</s>
<s>
Modeless	B-General_Concept
interfaces	B-Application
avoid	O
mode	O
errors	O
,	O
in	O
which	O
the	O
user	O
performs	O
an	O
action	O
appropriate	O
to	O
one	O
mode	O
while	O
in	O
another	O
mode	O
,	O
by	O
making	O
it	O
impossible	O
for	O
the	O
user	O
to	O
commit	O
them	O
.	O
</s>
<s>
In	O
his	O
book	O
The	O
Humane	O
Interface	B-Application
,	O
Jef	O
Raskin	O
defines	O
modality	O
as	O
follows	O
:	O
</s>
<s>
state.	O
"	O
</s>
<s>
In	O
Raskin	O
's	O
sense	O
and	O
according	O
to	O
his	O
definition	O
,	O
an	O
interface	B-Application
is	O
not	O
modal	O
as	O
long	O
as	O
the	O
user	O
is	O
fully	O
aware	O
of	O
its	O
current	O
state	B-Application
.	O
</s>
<s>
Typically	O
a	O
user	O
is	O
aware	O
of	O
a	O
system	O
state	B-Application
if	O
the	O
state	B-Application
change	O
was	O
purposefully	O
initiated	O
by	O
the	O
user	O
,	O
or	O
if	O
the	O
system	O
gives	O
some	O
strong	O
signals	O
to	O
notify	O
the	O
user	O
of	O
the	O
state	B-Application
change	O
in	O
the	O
place	O
where	O
interaction	O
occurs	O
.	O
</s>
<s>
If	O
the	O
user	O
's	O
locus	O
of	O
attention	O
changes	O
to	O
a	O
different	O
area	O
,	O
the	O
state	B-Application
of	O
the	O
interface	B-Application
may	O
then	O
represent	O
a	O
mode	O
since	O
the	O
user	O
is	O
no	O
longer	O
aware	O
of	O
it	O
.	O
</s>
<s>
Larry	O
Tesler	O
defined	O
modes	O
as	O
"	O
a	O
state	B-Application
of	O
the	O
user	B-Application
interface	I-Application
that	O
lasts	O
for	O
a	O
period	O
of	O
time	O
,	O
is	O
not	O
associated	O
with	O
any	O
particular	O
object	O
,	O
and	O
has	O
no	O
role	O
other	O
than	O
to	O
place	O
an	O
interpretation	O
on	O
operator	O
input.	O
"	O
</s>
<s>
Several	O
examples	O
of	O
software	O
have	O
been	O
described	O
as	O
modal	O
or	O
using	O
interface	B-Application
modes	O
:	O
</s>
<s>
Text	B-Application
editors	I-Application
–	O
typically	O
are	O
in	O
insert	B-Device
mode	I-Device
by	O
default	O
but	O
can	O
be	O
toggled	O
in	O
and	O
out	O
of	O
overtype	B-Device
mode	I-Device
by	O
pressing	O
the	O
Insert	B-Device
key	I-Device
.	O
</s>
<s>
vi	B-Application
–	O
has	O
one	O
mode	O
for	O
inserting	O
text	O
,	O
and	O
a	O
separate	O
mode	O
for	O
entering	O
commands	O
.	O
</s>
<s>
There	O
is	O
also	O
an	O
"	O
ex	B-Device
"	O
mode	O
for	O
issuing	O
more	O
complex	O
commands	O
(	O
e.g.	O
</s>
<s>
Emacs	B-Application
–	O
has	O
the	O
concept	O
of	O
"	O
prefix	O
keys	O
"	O
,	O
which	O
trigger	O
a	O
modal	O
state	B-Application
by	O
pressing	O
the	O
control	B-Device
key	I-Device
plus	O
a	O
letter	O
key	O
.	O
</s>
<s>
Emacs	B-Application
then	O
waits	O
for	O
additional	O
keypresses	O
that	O
complete	O
a	O
keybinding	O
.	O
</s>
<s>
This	O
differs	O
from	O
vi	B-Application
in	O
that	O
the	O
mode	O
always	O
ends	O
as	O
soon	O
as	O
the	O
command	O
is	O
called	O
(	O
when	O
the	O
sequence	O
of	O
key	O
presses	O
that	O
activates	O
it	O
is	O
completed	O
)	O
.	O
</s>
<s>
Emacs	B-Application
also	O
has	O
many	O
"	O
major	O
and	O
minor	O
"	O
modes	O
that	O
change	O
the	O
available	O
commands	O
,	O
and	O
may	O
be	O
automatically	O
invoked	O
based	O
on	O
file	O
type	O
to	O
more	O
easily	O
edit	O
files	O
of	O
that	O
type	O
.	O
</s>
<s>
Emacs	B-Application
modes	O
are	O
not	O
restricted	O
to	O
editing	O
text	O
files	O
;	O
modes	O
exist	O
for	O
file	B-Application
browsing	I-Application
,	O
web	O
browsing	O
,	O
IRC	B-Protocol
and	O
email	O
and	O
their	O
interaction	O
patterns	O
are	O
equivalent	O
to	O
application	B-Application
software	I-Application
within	O
the	O
Emacs	B-Application
environment	O
.	O
</s>
<s>
Modes	O
are	O
written	O
in	O
Emacs	B-Operating_System
Lisp	I-Operating_System
,	O
and	O
all	O
modes	O
may	O
not	O
be	O
included	O
with	O
all	O
versions	O
.	O
</s>
<s>
Cisco	B-Protocol
IOS	I-Protocol
–	O
certain	O
commands	O
are	O
executed	O
in	O
a	O
"	O
command	O
mode	O
"	O
.	O
</s>
<s>
Tools	O
chosen	O
from	O
a	O
palette	B-Data_Structure
in	O
photo-editing	O
and	O
drawing	O
applications	O
are	O
examples	O
of	O
a	O
modal	O
interface	B-Application
.	O
</s>
<s>
Releasing	O
the	O
key	O
returns	O
the	O
interface	B-Application
to	O
the	O
modal	O
tool	O
activated	O
by	O
the	O
palette	B-Data_Structure
.	O
</s>
<s>
Modal	O
windows	O
block	O
all	O
workflow	B-Operating_System
in	O
the	O
top-level	O
program	O
until	O
the	O
modal	O
window	O
is	O
closed	O
.	O
</s>
<s>
Larry	O
Tesler	O
at	O
PARC	O
devised	O
insights	O
for	O
a	O
modeless	B-General_Concept
word	B-General_Concept
processor	I-General_Concept
from	O
the	O
feedback	O
gathered	O
from	O
a	O
user	O
test	O
with	O
newly-hired	O
Sylvia	O
Adams	O
,	O
where	O
she	O
was	O
asked	O
to	O
ad	O
lib	O
some	O
gestures	O
to	O
correct	O
proofreading	O
marks	O
on	O
the	O
digital	O
text	O
.	O
</s>
<s>
This	O
test	O
convinced	O
Tesler	O
's	O
manager	O
Bill	O
English	O
of	O
the	O
problems	O
with	O
their	O
previous	O
modal	O
interface	B-Application
.	O
</s>
<s>
Modes	O
are	O
often	O
frowned	O
upon	O
in	O
interface	B-Application
design	O
because	O
they	O
are	O
likely	O
to	O
produce	O
mode	O
errors	O
when	O
the	O
user	O
forgets	O
what	O
state	B-Application
the	O
interface	B-Application
is	O
in	O
,	O
performs	O
an	O
action	O
that	O
is	O
appropriate	O
to	O
a	O
different	O
mode	O
,	O
and	O
gets	O
an	O
unexpected	O
and	O
undesired	O
response	O
.	O
</s>
<s>
Problems	O
occur	O
if	O
a	O
change	O
in	O
the	O
system	O
state	B-Application
happens	O
unnoticed	O
(	O
initiated	O
by	O
the	O
system	O
,	O
or	O
by	O
another	O
person	O
,	O
such	O
as	O
the	O
user	O
who	O
was	O
previously	O
using	O
the	O
machine	O
)	O
,	O
or	O
if	O
after	O
some	O
time	O
the	O
user	O
forgets	O
about	O
the	O
state	B-Application
change	O
.	O
</s>
<s>
Another	O
typical	O
problem	O
is	O
a	O
sudden	O
change	O
of	O
state	B-Application
that	O
interrupts	O
a	O
user	O
's	O
activity	O
,	O
such	O
as	O
focus	B-Application
stealing	I-Application
.	O
</s>
<s>
In	O
such	O
a	O
situation	O
it	O
can	O
easily	O
happen	O
that	O
the	O
user	O
does	O
some	O
operations	O
with	O
the	O
old	O
state	B-Application
in	O
mind	O
,	O
while	O
the	O
brain	O
has	O
not	O
yet	O
fully	O
processed	O
the	O
signals	O
indicating	O
the	O
state	B-Application
change	O
.	O
</s>
<s>
The	O
most	O
common	O
source	O
of	O
mode	O
errors	O
may	O
be	O
the	O
Caps	B-Device
Lock	I-Device
key	I-Device
.	O
</s>
<s>
Other	O
common	O
modes	O
available	O
in	O
PC	B-Device
keyboards	I-Device
are	O
the	O
other	O
lock	B-Device
keys	I-Device
,	O
Num	B-Device
lock	I-Device
and	O
Scroll	B-Device
lock	I-Device
,	O
and	O
often	O
the	O
Insert	B-Device
key	I-Device
.	O
</s>
<s>
Dead	B-Device
keys	I-Device
for	O
diacritics	O
also	O
create	O
a	O
short-term	O
mode	O
,	O
at	O
least	O
if	O
they	O
do	O
n't	O
provide	O
visual	O
feedback	O
that	O
the	O
next	O
typed	O
character	O
will	O
be	O
modified	O
.	O
</s>
<s>
While	O
the	O
Lock	B-Device
keys	I-Device
on	O
PC	B-Device
keyboards	I-Device
are	O
designed	O
with	O
the	O
intention	O
that	O
they	O
be	O
used	O
as	O
modal	O
keys	O
,	O
the	O
IBM	O
PC	O
hardware	O
design	O
does	O
not	O
require	O
these	O
nor	O
any	O
other	O
specific	O
keys	O
to	O
be	O
modal	O
but	O
allows	O
software	O
to	O
treat	O
any	O
key	O
as	O
modal	O
.	O
</s>
<s>
(	O
The	O
PC	B-Operating_System
BIOS	I-Operating_System
normally	O
implements	O
Caps	B-Device
Lock	I-Device
,	O
Num	B-Device
Lock	I-Device
,	O
and	O
Scroll	B-Device
Lock	I-Device
states	O
,	O
so	O
the	O
modality	O
of	O
these	O
keys	O
may	O
appear	O
intrinsic	O
,	O
but	O
it	O
is	O
neither	O
technically	O
nor	O
practically	O
necessary	O
to	O
use	O
the	O
BIOS	B-Operating_System
for	O
keyboard	B-Device
I/O	B-General_Concept
,	O
and	O
in	O
fact	O
most	O
modern	O
operating	O
systems	O
do	O
not	O
use	O
BIOS	B-Operating_System
keyboard	B-Device
I/O	B-General_Concept
.	O
)	O
</s>
<s>
PC	O
users	O
whose	O
language	O
is	O
not	O
based	O
on	O
the	O
Latin	O
alphabet	O
commonly	O
have	O
to	O
interact	O
using	O
two	O
different	O
keyboard	B-Device
layouts	O
:	O
a	O
local	O
one	O
and	O
QWERTY	O
.	O
</s>
<s>
This	O
gives	O
rise	O
to	O
mode	O
errors	O
linked	O
to	O
the	O
current	O
keyboard	B-Device
layout	O
:	O
quite	O
often	O
,	O
the	O
synchronization	O
of	O
"	O
current	O
layout	O
"	O
mode	O
between	O
the	O
human	O
and	O
the	O
interface	B-Application
is	O
lost	O
,	O
and	O
text	O
is	O
typed	O
in	O
a	O
layout	O
which	O
is	O
not	O
the	O
intended	O
one	O
,	O
producing	O
meaningless	O
text	O
and	O
confusion	O
.	O
</s>
<s>
Keyboard	B-Device
keys	O
in	O
user	B-Application
interface	I-Application
elements	O
like	O
"	O
(	O
y/n	O
)	O
"	O
can	O
have	O
opposite	O
effect	O
if	O
a	O
program	O
is	O
translated	O
.	O
</s>
<s>
A	O
frequent	O
example	O
is	O
the	O
sudden	O
appearance	O
of	O
a	O
modal	O
error	O
dialog	O
in	O
an	O
application	O
while	O
the	O
user	O
is	O
typing	O
,	O
known	O
as	O
focus	B-Application
stealing	I-Application
;	O
the	O
user	O
expects	O
the	O
typed	O
text	O
to	O
be	O
introduced	O
into	O
a	O
text	O
field	O
,	O
but	O
the	O
unexpected	O
dialog	O
may	O
discard	O
all	O
the	O
input	O
,	O
or	O
may	O
interpret	O
some	O
keystrokes	O
(	O
like	O
"	O
Y	O
"	O
for	O
"	O
yes	O
"	O
and	O
"	O
N	O
"	O
for	O
"	O
no	O
"	O
)	O
in	O
a	O
way	O
that	O
the	O
user	O
did	O
not	O
intend	O
,	O
often	O
triggering	O
a	O
destructive	O
action	O
that	O
can	O
not	O
be	O
reverted	B-Application
.	O
</s>
<s>
The	O
Unix	B-Application
text	B-Application
editor	I-Application
vi	B-Application
can	O
be	O
notoriously	O
difficult	O
for	O
beginners	O
precisely	O
because	O
it	O
uses	O
modes	O
,	O
and	O
because	O
earlier	O
versions	O
configured	O
mode	O
indication	O
to	O
be	O
turned	O
off	O
by	O
default	O
.	O
</s>
<s>
In	O
many	O
computer	O
video	O
games	O
,	O
the	O
keyboard	B-Device
is	O
used	O
both	O
for	O
controlling	O
the	O
game	O
and	O
typing	O
messages	O
.	O
</s>
<s>
Actually	O
making	O
the	O
action	O
reversible	O
(	O
providing	O
an	O
"	O
undo	B-Application
"	O
option	O
)	O
is	O
recommended	O
instead	O
.	O
</s>
<s>
Modal	O
interfaces	B-Application
require	O
training	O
and	O
experience	O
to	O
avoid	O
mode	O
errors	O
like	O
these	O
.	O
</s>
<s>
Interface	B-Application
expert	O
Jef	O
Raskin	O
came	O
out	O
strongly	O
against	O
modes	O
,	O
writing	O
,	O
"	O
Modes	O
are	O
a	O
significant	O
source	O
of	O
errors	O
,	O
confusion	O
,	O
unnecessary	O
restrictions	O
,	O
and	O
complexity	O
in	O
interfaces.	O
"	O
</s>
<s>
Later	O
he	O
notes	O
,	O
"	O
'	O
It	O
is	O
no	O
accident	O
that	O
swearing	O
is	O
denoted	O
by	O
#&%	O
!	O
#$&	O
,	O
'	O
writes	O
my	O
colleague	O
,	O
Dr.	O
James	O
Winter	O
;	O
it	O
is	O
'	O
what	O
a	O
typewriter	O
used	O
to	O
do	O
when	O
you	O
typed	O
numbers	O
when	O
the	O
Caps	B-Device
Lock	I-Device
was	O
engaged	O
 '	O
.	O
"	O
</s>
<s>
Raskin	O
dedicated	O
his	O
book	O
The	O
Humane	O
Interface	B-Application
to	O
describe	O
the	O
principles	O
of	O
a	O
modeless	B-General_Concept
interface	B-Application
for	O
computers	O
.	O
</s>
<s>
Those	O
principles	O
were	O
implemented	O
in	O
the	O
Canon	B-Device
Cat	I-Device
and	O
Archy	B-Application
systems	O
.	O
</s>
<s>
Some	O
interface	B-Application
designers	O
have	O
recently	O
taken	O
steps	O
to	O
make	O
modal	O
windows	O
more	O
obvious	O
and	O
user	O
friendly	O
by	O
darkening	O
the	O
background	O
behind	O
the	O
window	O
or	O
allowing	O
any	O
mouse	O
click	O
outside	O
of	O
the	O
modal	O
window	O
to	O
force	O
the	O
window	O
to	O
close	O
–	O
a	O
design	O
called	O
a	O
Lightbox	B-Language
–	O
thus	O
alleviating	O
the	O
risk	O
of	O
modal	O
errors	O
.	O
</s>
<s>
For	O
this	O
goal	O
,	O
the	O
Lightbox	B-Language
design	O
provides	O
strong	O
visual	O
contrast	O
of	O
the	O
dialog	O
over	O
the	O
rest	O
of	O
the	O
visuals	O
.	O
</s>
<s>
Bruce	O
Wyman	O
,	O
the	O
designer	O
of	O
a	O
multi-touch	B-Application
table	O
for	O
a	O
Denver	O
Art	O
Museum	O
art	O
exhibition	O
argues	O
that	O
interfaces	B-Application
for	O
several	O
simultaneous	O
users	O
must	O
be	O
modeless	B-General_Concept
,	O
in	O
order	O
to	O
avoid	O
bringing	O
any	O
single	O
user	O
into	O
focus	O
.	O
</s>
<s>
Alternatives	O
to	O
modes	O
such	O
as	O
the	O
undo	B-Application
command	I-Application
and	O
the	O
recycle	B-Application
bin	I-Application
are	O
recommended	O
when	O
possible	O
.	O
</s>
<s>
HCI	O
researcher	O
Donald	O
Norman	O
argues	O
that	O
the	O
best	O
way	O
to	O
avoid	O
mode	O
errors	O
,	O
in	O
addition	O
to	O
clear	O
indications	O
of	O
state	B-Application
,	O
is	O
helping	O
the	O
users	O
to	O
construct	O
an	O
accurate	O
mental	O
model	O
of	O
the	O
system	O
which	O
will	O
allow	O
them	O
to	O
predict	O
the	O
mode	O
accurately	O
.	O
</s>
<s>
After	O
completing	O
the	O
task	O
for	O
which	O
the	O
mode	O
was	O
activated	O
,	O
or	O
after	O
a	O
cancel	O
action	O
such	O
as	O
the	O
Escape	B-Device
key	I-Device
,	O
returning	O
to	O
the	O
previous	O
state	B-Application
when	O
a	O
mode	O
is	O
dismissed	O
will	O
reduce	O
the	O
negative	O
impact	O
.	O
</s>
<s>
In	O
the	O
book	O
The	O
Humane	O
Interface	B-Application
,	O
Jef	O
Raskin	O
championed	O
what	O
he	O
termed	O
quasimodes	O
,	O
which	O
are	O
modes	O
that	O
are	O
kept	O
in	O
place	O
only	O
through	O
some	O
constant	O
action	O
on	O
the	O
part	O
of	O
the	O
user	O
;	O
such	O
modes	O
are	O
also	O
called	O
spring-loaded	O
modes	O
.	O
</s>
<s>
Modifier	B-Device
keys	I-Device
on	O
the	O
keyboard	B-Device
,	O
such	O
as	O
the	O
Shift	B-Device
key	I-Device
,	O
the	O
Alt	B-Device
key	I-Device
and	O
the	O
Control	B-Device
key	I-Device
,	O
are	O
all	O
examples	O
of	O
a	O
quasimodal	O
interface	B-Application
.	O
</s>
<s>
The	O
purported	O
benefit	O
of	O
this	O
technique	O
is	O
that	O
the	O
user	O
does	O
n't	O
have	O
to	O
remember	O
the	O
current	O
state	B-Application
of	O
the	O
application	O
when	O
invoking	O
a	O
command	O
:	O
the	O
same	O
action	O
will	O
always	O
produce	O
the	O
same	O
perceived	O
result	O
.	O
</s>
<s>
An	O
interface	B-Application
that	O
uses	O
quasimodes	O
only	O
and	O
has	O
no	O
full	O
modes	O
is	O
still	O
modeless	B-General_Concept
according	O
to	O
Raskin	O
's	O
definition	O
.	O
</s>
<s>
The	O
StickyKeys	B-Device
feature	O
turns	O
a	O
quasimode	O
into	O
a	O
mode	O
by	O
serializing	O
keystrokes	O
of	O
modifier	B-Device
keys	I-Device
with	O
normal	O
keys	O
,	O
so	O
that	O
they	O
do	O
n't	O
have	O
to	O
be	O
pressed	O
simultaneously	O
.	O
</s>
