Gallery macro rendered incorrectly on Opera browsers

When viewing the gallery macro from opera browsers the picture is rendered at the bottom of the whole page not over the current view.

To reproduce the problem:
Start Opera 9.50 (doubt that version matters)
Open http://wikis.sun.com/display/gridengine62u2/Express+Installation page
Click on series of 4 pictures (gallery macro)
=> You don't get the picture just the black effect. Picture is actually
rendered, but after the end of screen. One has to scroll down to the end of the
document!