notnull
more readable error
cleanup
do not log PCE
assert isDispatchThread
moved CommandProcessor to core
Platform: OS X scrollbars: removed JLayeredPane-hack to avoid problems like:
IDEA-125075 Database tools navigation problems: PgUp / PgDown
IDEA-122956 Popups in Project Structure dialog have wrong initial size sometimes

The trick is to return 'false' isOptimizedDrawingEnabled when we have overlaid scrollbars (same trick is used by JLayeredPane)