using wp3.4.2+tinymce advanced 3.5.8, all inline popup dialogs open, but remain blank. on the body tag in the iframe, it says style='display:none'. in the invisible content, the labels and texts are untranslated. in short, tinyMCEPopup did not init.
this is ofcourse due to tiny_mce_popup.js, and i bluntly replaced it with the latest version i could find, here
and lo, everything worked.