Ok, here is something closer. Not sure if that will be good enough, but...
Attached and here:
<!--Saved by Quest 5.5.5328.26617-->
<asl version="550">
<include ref="English.aslx" />
<include ref="Core.aslx" />
<game name="scrolltest">
<gameid>6c7b6532-6d01-4197-9700-4ed697ba78aa</gameid>
<version>1.0</version>
<firstpublished>2014</firstpublished>
<js>
<![CDATA[
<script type="text/javascript">
var next_section = 0;
function scrollOffTop() {
var name = "scrollsection" + next_section++;
StartOutputSection(name);
var height = $(window).height() - $("#status").height() - $("#txtCommandSpacer").height() - $("#txtCommandDiv").height() - 35;
console.log(name + ", " + height);
addText("<div style='height:" + height + "px'> </div>");
EndOutputSection(name);
HideOutputSection(name);
}
</script>
]]>
</js>
<start type="script">
OutputTextNoBr(game.js)
</start>
</game>
<object name="room">
<inherit name="editor_room" />
<description type="script">
<![CDATA[
JS.scrollOffTop()
msg ("You are in a weirdly scrolling room! Everywhere you look, things keep shifting and moving.")
]]>
</description>
<object name="player">
<inherit name="editor_object" />
<inherit name="editor_player" />
</object>
</object>
</asl>
The hard-coded "35" in there was an eyeball sum of the border and padding values for the various containers. It could be made more rigid by actually referencing the element attributes, but should be good enough for now.