[whpalmer4]

Baseline TIFF doesn't support layers. OmniGraffle is using the format with the widest compatibility.

If you want to make a feature request, use Help->Send Feedback inside the application. It's also the best route to use if you want a guaranteed answer from Omni; queries to the forum may or may not be seen and answered, but email via Help->Send Feedback goes into their tracking system.