Re: [cssom-view] Easing the transition to spec-compatible body scrollTop behavior

Hi Rick

We’re looking at implementing scrollingElement in WebKit, and are confused by a few things in the spec[1]:

1. We’d like to see some text to explain the purpose of this API, perhaps with an example of use (in a quirky and a non-quirky document), and a description of what exactly scrollingElement is intended to represent.

2. In the first step, the negated reference to the body being “potentially scrollable” is very confusing, because the definition of “potential scrollable” has a clause that references the body and the root’s scrollability. We’re finding that the multiple negations make the logic hard to follow. It would also help to use a term that’s more descriptive than “potential scrollable”. Is this more like independently scrollable, or scrollable via overflow?

3. The steps and the Note about non-conforming user agents imply that there will be a behavior change for non-conforming user agents when they start to conform. Currently they will always return the body. In future, they will return null for some combination of non-visible overflow on the body and the documentElement. Is that intended?

Simon

[1] http://dev.w3.org/csswg/cssom-view/#dom-document-scrollingelement <http://dev.w3.org/csswg/cssom-view/#dom-document-scrollingelement>
[2] http://dev.w3.org/csswg/cssom-view/#potentially-scrollable <http://dev.w3.org/csswg/cssom-view/#potentially-scrollable>