Known Bugs

* Cost values do not update after the formula of a derived event type
  was changed. One has to change to another event type and back (9/2011)

  Reason: For derived event types, class ProfileCostArray caches the cost,
  calculated from the formula, as this is used multiple times. The cache
  is only invalidated when the cost of another event type is requested.

  Possible fix: Invalidate the cache of every cost item after a formula
  change. Tricky and takes time. Better allocate a new event type and
  remove old?

* KCachegrind allows two event types to be shown. If they are set to the
  same, and this event type is removed, KCachegrind crashes.

  Reason: By design, only one of the event types can be changed at a time.
  Still, on a change, the cost for the other event type is updated. As
  the event type is already deleted, the crash happens.

  Possible fix: delete event type after selecting another event type before.
  Tricky, as change actions are delayed by a timer.
  Another fix: do not allow the two event types to be the same.
