Should be addressed in virt-viewer 1.0 or newer ( https://git.fedorahosted.org/cgit/virt-viewer.git/commit/?id=d1d53d0c8b5600f61e55e472c592ebc86a65ee6f ) and spice-gtk 0.24 or newer ( http://cgit.freedesktop.org/spice/spice-gtk/commit/?id=8cbdc3d2d6ca6d8f9b8e75c0c11f0e89f4427eb2 and previous commits). The 3.6 rebase will have these versions (and a new enough glib) so this should address this RFE.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://rhn.redhat.com/errata/RHEA-2016-0377.html