If you're using the 'browser' font tweak on a K3, expect some kind of breakage on 3.4. I'd recommend disabling this for now (recreating the empty 'nobrowser' file from a default install). The next update should take the necessary changes into account, but I can't guarantee the feature will still work correctly. It might be necessary for custom fonts in KF8 files, though, so it'll take a bit of time for me to look into that as well...
(By default, this tweak is NOT enabled, so, if you're wondering what the hell it is, there's a good chance you're not using it
).
Other than that, the 3.4 update seems pretty hack-friendly (at least for the stuff in this thread), for now...