Operating system resources in SWT refer to native resources used by those (operating system) resourcebased objects, e.g. Display, Color, Font, GC, Image, Printer, Region, and Widgets. Most of the classes in the following packages are resource-based:
org.eclipse.swt.custom org.eclipse.swt.graphics org.eclipse.swt.widgets
You can check whether a class has a dispose() method. If it does, then it is very likely resource-based. Otherwise, it isn't.