keyboard based app locking

timjph says:
The problem with ipads, especially if they are used by family members, is that they have no privacy. In many ways this is a problem with iOS. As a solution for now it would be nice if you could set a 4 digit code on the RTM app, so that others couldn't use it, but you didn't have to enter your RTM password/reinitialize each time. Its just too easy for someone else to delete a load of RTM tasks while playing...