Needs to be recompiled with gtkmm 2.6.9. Could you please queue a rebuild ? Thanks.
Looks like an MIA package maintainer. Perhaps you can email him directly? Also, we have this (offically now): http://fedoraproject.org/wiki/Extras/Policy/AWOL_Maintainers So you might want to review that.
The 2.6.9 gtkmm release was a mistake that should never have happened (was not meant to break ABI). So I'll release 2.6.10 and that should fix the wp_tray problem as well.
The gtkmm 2.6.10 release fixed the problem.