[whpalmer4]

You don't, assuming I've understood your question correctly. I take it you want to select several actions and drag their depiction on the Gantt chart forward or backward to a different date/time? You don't really want to be in the practice of setting the dates for large numbers of your actions in this fashion, because it handicaps OmniPlan's ability to move things around. Better to have it work out the dates/times based on dependencies and lead times and set as few dates as possible.