(off-topic from ubuntu's ui problems at this point, but...)

yeah, Android uses a system property to communicate system-wide timezone changes. in libc, where tzcode checks the environment variable, we check the system property.

annoyingly we _also_ check the environment variable, which is useful for command-line stuff (where it's a workaround for the lack of functions in POSIX that take an explicit timezone). this shows up in profiles even; if you profile the logcat command which takes a bunch of timestamps and formats them, it spends a depressing amount of time in getenv(). the system properties stuff is cheap to ask "has it changed?" after your first lookup. theoretically i could make the environment functions try to keep track of changes, but putenv() breaks that. (environ is no great help either.) i guess i could look for putenv() with "TZ=" and have another "all bets are off" flag, but, well, i've never been quite annoyed enough by logcat's performance issues to try to go there.