The "tracks aren't connected unless the ends meet" bit is exceedingly annoying, but it's small enough that rather than immediately pissing me off and sending me scurrying for the bug report form, it's been slowly driving me insane instead!
That one
needs a bug report filed. On a complex board, it can be really hard to track down the bad connection when it decides that a connection hasn't been made. It doesn't help that it makes no attempt to hint at where it might be - instead of finding the two nearest points and showing them as disconnected, it just finds
any two points...