RE: Style guide: tristatecheckbox

In the ARIA spec, it's not our job to tell developers what to do -- just 
to make it possible to do it accessibly.

- Aaron

"Sailesh Panchang" <> 
Sent by:
04/14/2008 08:17 PM
Please respond to

Aaron M Leventhal/Cambridge/IBM@IBMUS
<>, <>
RE: Style guide: tristatecheckbox

In reality a 3-state checkbox is  a poorly designed control.
In the example  with a tree control and checkbox / radio buttons for 
underlying components, the installation process might require the user to 
indicate selections against all components (mandatory). 
Or  it may not be mandatory in which case default selections would be used 
I assume.
If it is mandatory, it does not matter if the user has not indicated 
selections against 1 or all components. Till all are indicated, the state 
of the parent control is incomplete or unchecked. A more useful state for 
a parent control of this nature would be one which indicates count (out of 
a max possible) that are answered like 7/12 i.e. 7 have been answered and 
5 are unanswered.
Radio and checkbox controls are essentially boolean and should be retained 
that way.
Microsoft regards       a tri-state checkbox is a group of three radio 
buttons, two of which represent the false and the true states and a third 
which stands for the undefined state. Not sure why  this is needed. A null 
value is returned for the undefined state anyway.
Not sure if this is open for debate here.

From: Aaron M Leventhal [] 
Sent: Monday, April 14, 2008 10:20 AM
Subject: RE: Style guide: tristatecheckbox


It's not common, but here is a use case on the desktop today: 
In an installer, you may have a tree view of components to select. Each 
item in the tree view is a tristate checkbox. If only some of the some 
items are checked, then the checkbox is shown as "mixed". 

- Aaron 

"Sailesh Panchang" <> 
Sent by: 
04/14/2008 04:24 PM 

Please respond to

Aaron M Leventhal/Cambridge/IBM@IBMUS, <> 
RE: Style guide: tristatecheckbox


I question the concept of a partially checked checkbox. 
Checkbox and radio buttons are meant to hold  just the 2 boolean values: 
yes or no. 
If one can have  a 3 state checkbox  (to correspond to Yes, No, Not sure), 
then why not a 5 state checkbox (that corresponds with something like 
Strongly agree, Agree, Not decided, Disagree, Strongly disagree)? 
Sailesh Panchang
Accessibility Services Manager (Web and Software)
Deque Systems Inc. (
11130 Sunrise Valley Drive, Suite #140,
Reston VA 20191
Phone: 703-225-0380 (ext 105)

From: [] On Behalf 
Of Aaron M Leventhal
Sent: Friday, April 11, 2008 6:11 AM
Subject: Style guide: tristatecheckbox 

The below definition conflicts with itself. 
If the item is partially checked, space rotates through checked, unchecked 
and then partially checked again. 
However, the first bullet says if it's not checked that space  checks it! 

Is the implementation supposed to have 2 different code paths for 
unchecked checkboxes depending on whether it was originally partially 

- Aaron 
Three State Check Box 
If not checked, space checks the check box 
If checked, space unchecks the check box 
If partially checked, space will rotate through checked, unchecked, and 
partially checked states.

Received on Monday, 14 April 2008 18:57:29 UTC