The debugger helped a lot figuring this out. The easiest way is to create a custom actor with a tick function adding a break point to the beginning of the function; using the debugger one can easily see the call stack. Alternately, you can also perform an "informed’ crash by dereferencing a null-pointer which will also yield the call stack in the crash reporter; the call stack looks much nicer in that reporter than in the debugger haha.
Is there something you are looking at in particular?