Primitive next_prime;
next_prime = null;
while ( drawables_itr.hasPrevious() ) {
itr_dobj = (Drawable) drawables_itr.previous();
if ( itr_dobj.overlaps( timeframe ) ) {
if ( itr_dobj instanceof Composite ) {
itr_cmplx = (Composite) itr_dobj;
itr_cmplx.addPrimitivesToSet( set_primes, timeframe );
try {
next_prime = (Primitive) set_primes.last();