Arima, In the case of 5,000 events you prefer this:
The first has no meaning beside counting events. It has no purpose too beside telling someone he/she has an error on event #40,321.
Your highlight idea is a good start/direction but it lacks the point I was trying to make - a mechanism which will show you how deep your current event is.
That's exactly what my idea is - the vertical lines CC has accomplish that in a much more elegant fashion IMO.
Honestly, I can't think of any reason to want to know how deep an event is. That information alone, without the context of the conditions in the events above it is pretty much useless to me. Using CC's vertical lines, I can tell what events are on what level. That system is a lot cleaner and works just fine. If the line of the currently selected event was highlighted, that would be even better.
You also forgot my prediction - events will be able to fold in the future. With my suggestion you won't see the mess you mentioned in the 18.104.22.168.22.214.171.124.9 scenario (have you really gone so deep?)
Even when sub event collapsing is implemented, I would still have to look at it when working with those events! That wouldn't make any difference.
Do I prefer event 1981 to event 126.96.36.199.188.8.131.52.1.6.1? Vastly! Much simpler, much smaller, less keys to press, less likely for a typo, easier to read, much easier and faster to process mentally. Tell me at a glance - which is higher in the event sheet, event 184.108.40.206.220.127.116.11.1.6.1 or event 18.104.22.168.22.214.171.124.6.1? Comparing event 1981 and event 1960 is far quicker and easier.