?
There isn't really any room for any error... It isn't like you would have to enter a number they would probably make it a slider. There is already partitioning... and other than having a range to work with... I don't see how you could add anything else. The partitioning of other types of file systems and such on the otherOS partition space should (and can easily) be taken care of by programs within an otherOS. They don't need to impliment anything of that sort... there is simply no need to. But I definitely see the range for partition space as very safe and no room for error.