This problem was detected in APEX Version 4.2.0.00.27
This issue occured when I developed an application usign Theme 25.
When viewing the Modal regions in IE8 (not sure about later versions), the page appeared like this:
This is a simple fix. You will need to add some css to each page that you are using the modal template on.
1) Edit the page
2) Edit the page definition (the top node in 'Page Rendering')
3) Scroll down to the CSS Section.
4) In the Inline area, add this css:
display: block !important;
The page should now display correctly:
This solution was provided by Shakeeb. See the Forum post here: https://forums.oracle.com/forums/thread.jspa?messageID=10686196