[whpalmer4]

Fred, exactly what do you want OmniPlan to do? Just set your effort percentage for that task to 20 / <number of work hours in four weeks for the resource>? That's not really ideal, as it prevents you from scheduling any task which requires more than the amount left over until that task is over. If we figure there are 160 hours in four weeks, that means you've got a task bar that occupies 12.5% of 100% for four weeks, and if you try to schedule a task at more than 87.5% of 100% effort for that resource anywhere during those four weeks, you'll either get a violation, or it won't be scheduled until after the four weeks. OmniPlan will not schedule a request to do 4 days of 100% of 100% into 5 days of 80% at 100%.

Both of you should send email via Help->Send Feedback to get your requests in front of the developers.