Virtual midnight should be evaluated in the time zone of an entry
Right now it looks like it's evaluated in my computer's current timezone. However, if I (normal resident of -0600) go to Europe and log in +0100, that's the timezone in which 4am has meaning. Right now, if I leave those entries in my timelog once I get back to the US and change my timezone back to -0600, they'll error out since it'll say missing client for my "arrived" entries. It seems as though my workaround is to change the timezone on those timelog entries (!) to -0600 as well.
(The alternative would be to ditch the virtual midnight thing and just mandate some kind of standard "arrived" entry, which seems less error prone to me.)