Safari, small windows and DOMcollapse

I just had a lot of complaints telling me my free script DOMcollapse is crap (I sometimes wonder why I bother to offer these things as all you get is complaints, half of which caused by bad implementation /rant) as it doesn’t work in Safari in a certain situation.

The problem reproduction sounds like an old school text adventure:

For Safari only, it works in other browsers

• Load the page http://www.onlinetools.org/tools/domcollapse/

• collapse the open item
• make the browser window small enough to show a vertical scrollbar
• expand the element again.
• the scrollbar changes, but the section is not shown – unless you resize the window a bit once more

Is there any workaround? I don’t want to do things like window.resizeTo to force a refresh… And if I have to, is there a safe object detection that only targets Safari?