code: public synchronized void setUseRedo(final boolean useRedo) {
  		if (validState && this.useRedo && !useRedo) { // Remove Redo
  			redoQueue.clear();
  			redoStore.clear();
  		}
  		this.useRedo = useRedo;
  	}
docs: Use Redo system?
  
  @param useRedo (default true)