Back from MODXpo Cologne, I’d share some good ideas which I picked up there, concerning accessibility.
It catched us from behind: the insight that the MODX Manager is just a website, we can style it like any other website, applying all the good practices we already know.
Why not position the TVs in a configurable grid structure, so that your backend layout may represent the frontend layout? – That would be a UX goodie, one thing Typo3 does right.
Why not configure the colors in variables like in LESS/SASS, so that everybody may set their preferred color scheme, say a high contrast scheme? – That would be one good way to cater for persons with low vision. Another good way would be to allow for personal color schemes on OS or browser level. Just take care that no text and icons are in the background where they get extincted by a personal color scheme. See here how it is done: http://www.paciellogroup.com/blog/2010/01/high-contrast-proof-css-sprites/
Why not make the layout responsive to screen size? – That would cater for mobile users as well as for people with low vision who use low resolution or text enlargement.
From the point of accessibility, mobile web is a fortune, as there are some similar restrictions and requirements. What you would perhaps not do for accessibility, you easily do it for mobile. And some old-fashioned virtues, like progressive enhancement, come back into place.