elements with presentational content

Hi. Lately I run into examples of widgets having presentational content as
part of their implementation and that content is exposed to AT which is
unfortunate. For example a custom button

<div role="button">
  Presentational content
</div>

UAIG guide suggests [1] to exclude the content from the tree under certain
elements aka "Children of
objects<http://www.w3.org/WAI/PF/aria-implementation/#def_object>which
have the characteristic "Children Presentational: True":". It's not
clear with me what "Children Presentational" is and that's the first issue.
The second one the requirement prevents the author to create menu buttons
like:

<div role="button">Button
  <div role="button">menu button</div>
</div>

(check out XUL example [2]).

So the trick the author could do is to apply aria-hidden="true" on some
internal container
<div role="button">
  <div aria-hidden="true">
    Presentational content
  </div>
</div>

Regardless the author have to introduce extra element in the hierarchy what
is not nice, this approach requires all browsers get agreed on aria-hidden
implementation.

Would it be good to introduce new attribute to let the author cut off the
content, for example
<div role="button" aria-leaf="true">

and can be defined as the browser should not expose any children for
element having aria-leaf="true" if the content serves the presentational
propose (like not focusable, not operable).

Alternative names: aria-nocontent, aria-nokids.

Would it be worth to have an extra attribute for that?

Thanks.
Alexander.

[1] http://www.w3.org/WAI/PF/aria-implementation/#exclude_elements2
[2]
https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XUL/PopupGuide/MenuButtons#The_%27menu-button%27_button