This issue is not panelDivider specific, when the ice:panelDivider is removed, I still see both problems outlined in ICE-7247.
Two IE7 styling issues are currently reproducible in the Williams poc:
1 - Header text is not moving with the dataTable. In the poc, when you expand the panel at the top, the datatable moves down but the header text does not.
2 - If you change the ace:dataTable in screen2.xhtml to the following, you will see the header columns bleed outside the width of the scrollbar and the column headers overlap the scrollbar :
<ace:dataTable rendered="#
{not screen2.graph}
"
value="#
{screen2.tableItems}
"
var="tableItem"
style="width:900px; overflow:auto;">
<ace:columnGroup type="header">
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
<ace:column headerText="Williams">Williams</ace:column>
</ace:columnGroup>
</ace:dataTable>
Adding before scroll and after scroll screenshot.