Interesting read. I once tracked clicks on a “enable high contrast”-button, but got unreliable results. Partly because of a bug in Internet Explorer, and partly because of poor HTML quality. It turned out that several (much used) “forms” were missing the form-tag. The contrast button, sitting at the top of the page, didn’t have the type-attribute (type=”button”). What happended was this:
When users pressed the Enter-key inside text inputs (that did not reside inside a form-tag), Internet Explorer fired a click event on the first available submit button in the page. That happened to be the “enable high contrast”-button. Since it didn’t have the type attribute specified, it defaulted to submit.. Lots of folks suddently got inverted colors whithout knowing what was going on :) And that probably also explained why so many turned the hight contrast mode off again.
The fix was to simply add type=”button” to the button, and to enclose input tags in form tags.. Moral is: Good HTML quality will get you far. You’ll even get more reliable statistics.