Few years ago I wrote a « how-to » post – FileMaker GO’s layouts, Slide a block method – about designing layouts for FileMaker Go with in mind a real iOS look and feel and how to deal with the rotation issue.
FileMaker have introduced a new script trigger OnRotation of the device. So you can use 2 different layouts to display the portrait and landscape view, but it’s twice the job…. I still prefer to work on one layout only.
this tutorial explains how to deal with the device rotation in this case