Until When May You Eat without a New Fore-Blessing

You may continue eating without saying a new fore-blessing--without a time limit--as long as you are not involved in some other activity that distracts you from eating (hesech da'at). 
Example
Situation You are eating and take a break to do work for your business or read a magazine article that involves your concentration.  
What To Do You may not continue eating unless you say a new fore-blessing.
Note This is true whether you became full at any time or not.