we actually just want to untip the clock, so make untipFor public. this prevents tips for the clock showing when the calendar is up, which is the intended behaviour, otherwise they show up over the calendar.

there is the use case where one might open the calendar, move it somewhere out of the way and then want to see the clock tip, but that's probably rather more rare than the "tip just popped up over my calendar!" problem (which was actually reported to me way back when).

the -best- fix would be to not show the tip if it would cover the calendar but ... yeah ... that's a lot of screwing around in the stable branch for a corner case.