Function flush_now 

pub fn flush_now()

Force a synchronous fixpoint drain now, even inside an open batch. Event dispatch wraps handlers in a batch (day-core), so a handler that needs its writes to drain immediately (namely with_animation, whose ambient animation must be live while the resulting patches apply) cannot rely on the batch’s close (that runs later, after the scope ends). This temporarily drops the batch depth so flush_sync runs, then restores it. No-op if a drain is already in progress (the writes fold into it); harmless if nothing is pending.