When double clicking on a file that contains Custom Types, SceneBuilder does not always propose to set up a classpath.

When opening a file that contains Unknow or Custom types, SceneBuilder should pop up a window proposing to resolve these types by setting up a classpath. This window opens when the file is opened using File > Open or File > Open Recent, but not when the file is opened from NetBeans, or by double clicking on the File System.
No warning is displayed - and elements of unresolved types are simply skipped.