HTML5 command element and images should support different resolutions

Hello! I've added the following to the wiki at http://www.w3.org/WAI/UA/work/wiki/HTML5_review_by_UAWG_notes#Command_element_and_images_should_support_different_resolutions:


    Command element and images should support different resolutions

Why allow multiple icons in different resolutions for a page icon but not for a command element icon or an img element?

*Use case:* Todd is working on a high resolution monitor but has moderately low vision, so he uses his browser's zoom setting so that he can read the text easily and discern the details of images. He goes to a web page that includes multiple buttons implemented using command elements, each represented by an icon. Unfortunately, since HTML5 only allows a command element to link to a single image, the browser has to use brute force methods to enlarge the image, with a result that's blocky and difficult to understand. If the author had been able to link to multiple versions of the image, each optimized for different screen resolutions or sizes, Todd could have been presented with graphical buttons he could understand.

*Recommendation:* HTML5 should allow the author to link a command element to multiple images optimized for different screen resolutions and zoom ratios.

It would also be beneficial to allow static images (e.g. the img element) to also link to multiple image files optimized for different resolutions, so that pages can better adapt to different screen resolutions and zoom ratios without having to resort to complex scripting. However, it could be argued that there are different priorities for the relative priority of applying this to command elements--which the user always has to identify to interact with them--and possibly static img element.