You need to include the proper SWT plugin for your machine in your run configuration.
1. Click Run -> Run Configurations... 2. Select the Run Configuration that is failing (on the left side) 3. Click the Plug-ins tab 4. In the "type filter text" box, type swt 5. Select the proper swt package for your machine. For me on OS X this was: org.eclipse.swt.cocoa.macosx.x86_64
Then run normally and it should work.