I have noticed some issues while working with FMA 15 while on macOS High Sierra 10.13. However, the issues seem to be greater in the recent beta that was released to Developers. I am having many window draw issues with the inspector, the main window and while opening new windows in my solutions. Sometimes this temporarily goes away with a restart of the system but not always.
I know this is development software but I wanted to alert the FileMaker development team to this issue as I am hoping to seem improvements with the compatibility of FMA15 with the newer macOS since not all of our users are able to move to version 16 at this time.