The SWT_AWT bug on OS is now closed with the release of 3.2RC3 and the apple swtcompatibilty patch if you want a quick test install the eclipse Metrics test in 3.1.x and run the graph viewer then run it in 3.2RC6 with the patch and it works
The patch can be downloaded from ADC
Just need the UML editor enabled in MyEclipse now 🙂