This is a problem that I find to be systemic in the HTML specs. Even in a world where every browser was somehow 100% compliant with the spec (never going to hap

This is a problem that I find to be systemic in the HTML specs. Even in a world where every browser was somehow 100% compliant with the spec (never going to happen), we web developers would still be hitting our heads against the wall with browser inconsistencies because the spec chooses to make important behavior optional or subject to the browser-vendor's unique implementation. Another example of this is HTML5 drag and drop, where things like what exactly starts a drag is left completely up to the browser, resulting in major differences in behavior between browsers, to the point of almost being unusable.