A small thing I noticed: Under Editor Preferences > Miscellaneous, if you currently hover over “Apply Lighting Automatically”, you get the (incorrect) tooltip that states “Whether to automatically save after a time interval”.
Similarly, under Sound, “Allow Background Audio” has no tooltip.
It looks like these might be set under UnrealEd/Classes/Settings/LevelEditorMiscSettings.h
I would post a quick patch if possible, but I don’t have a copy checked out at the moment.
I am running 4.3 from the Mac installer.