As a long term user of F9, I have to say that I'm surprised because the "dead keys" feature doesn't work in F10 under any WINE application (i.e., GoogleEarth). That is also true for Skype.
On the other hand, it works lovely in any Linux-native application (gEdit, Geany, OpenOffice, etc.)
I found this bugzilla report (https://bugzilla.redhat.com/show_bug.cgi?id=476439
) but, apparently, there is no solution yet...
This is annoying because, in my job, I really need Skype working properly in Spanish... I'll really appreciate any help about such an interesting situation ;-)