I read about these APIs in this webpage: http://www.ex-designz.net/apicat.asp?apicat=34
I tested TrackPopupMenuEx and TrackPopupMenu APIs and they do the same thing: displaying a menu at the cursor's position. The source codes are the same, you just have to add or erase the "Ex" at the end of the names of these APIs. Why two APIs for the same action?
Note: TrackPopupMenu crashes my app in runtime when used on an image control, while TrackPopupMenuEx works ok. TrackPopUpMenu seems to have no sense.