maybe i have found a bug in FileTreeComponent. i had it occasionaly to redraw itself incompletely - i.e., items were missing. i found that i can workaround it with throwing in some:
while( contentsList->isStillLoading() )
// maybe do some dummy-operation
in certain places. so my guess is, that it repaints itself while the embedded DirectoryContenstList is not yet fully built up. could that be? maybe some kind of callback from DirectoryContentsList to FileTreeComponent could be established to solve that in a more sound way?
btw.: the problem showed up only on OSX.