qemu-kvm 1.6.1-3.fc19.x86_64 uses a gtk gui as default, a change from the former SDL. It's nice and all, but has at least one alarming consequence. Whereas the SDL gui passed keycodes freely to the guest, the gtk one (with its menu bar) swallows the quite common ^Q and interprets it as a kill-the-vm command. Whoops! This surprising behavior+change should be well-documented in the man page, and ideally made configurable.
Looking at the QEMU code I don't see any attempt being made to disable accelerators/modifiers. There are 3 separate things that need to be disabled in GTK to ensure the guest sees every possible key sequence. QEMU will want to copy virt-viewer code for this probably https://git.fedorahosted.org/cgit/virt-viewer.git/tree/src/virt-viewer-window.c#n739
Patch posted upstream here, it just changes the shortcut to ctrl+alt+q: https://lists.gnu.org/archive/html/qemu-devel/2014-03/msg02679.html
qemu-1.6.2-1.fc20 has been submitted as an update for Fedora 20. https://admin.fedoraproject.org/updates/qemu-1.6.2-1.fc20
Package qemu-1.6.2-1.fc20: * should fix your issue, * was pushed to the Fedora 20 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing qemu-1.6.2-1.fc20' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2014-4134/qemu-1.6.2-1.fc20 then log in and leave karma (feedback).
qemu-1.6.2-1.fc20 has been pushed to the Fedora 20 stable repository. If problems still persist, please make note of it in this bug report.