[STYLE GUIDE] keyboard resizing of split containers

My definition of a split container is a section of the Web page which is 
split into two or more sections either horizontally or vertically.  Split 
containers can be nested to create both vertical and horizontal sections. 
A common implementation is for mail programs which usually provide a tree 
of folders on the left hand side of the page and on the right hand side of 
the page split into two sections stacked one above the other - one with a 
listing of the documents in the folder and another to preview the contents 
of the selected document.  Most applications provide a grab point on the 
border of the pane to resize the section using the mouse. 

Is a keyboard mechanism to resize a split container required to meet 
accessibility guidelines?  I am assuming yes since unless there are scroll 
bars some content might not be visible without resizing. 

I have some ideas for resizing with the keyboard.

1) Assign some key that when pressed when focus is within the section, 
will move focus to the grab point.  The user then modifies the size of the 
container using the mouse keys. This isn't particularly useful for screen 
reader users but I am hoping that they don't have to deal with the sizing 
problems because the screen reader will read all of the content even if it 
is clipped? 
2) Assign some key that when pressed when focus is within the section, 
will open a context menu with options for making smaller/larger by 10%, 
25%, 50%.
3) Shift-F10 from within the section will invoke a context menu with 
options for making the section smaller/larger by 10%, 25%, 50%,  If an 
application context menu for this section of the Web application already 
exists, the resize items would be appended to it.   This has the drawback 
that it is harder to implement, and will override the browsers context 
menu if there is no Web application defined context menu.  This could 
create a scenario where the user can not invoke the browsers context menu 
because the entire page is made up of re-sizable sections.  Of course that 
could also happen with any application defined context menu as well - but 
overriding the browser context menu just for resizing sections seems a bit 

I prefer option 1, although it has the disadvantage of a "special" key 
sequence that people will have to learn through discovery or good 
documentation.  But I also need screen reader user feedback to make sure 
this is sufficient. 


Becky Gibson
Web Accessibility Architect
IBM Emerging Internet Technologies
5 Technology Park Drive
Westford, MA 01886
Voice: 978 399-6101; t/l 333-6101
Email: gibsonb@us.ibm.com
blog: WebA11y

Received on Thursday, 13 September 2007 19:52:06 UTC