SceneBuilder 2.0 bundle on Mac doesn't allow to start the application.
The build 1 is built with FX 8 b104 and the build 2 with FX 8 b109; for both we get the same issue.
This issue is specific to Mac platform: Win and Linux are doing fine.

The application doesn't start when using the launcher produced by the FX packager. But if I construct a command line "java <my-options> <my-class>" then it does fine.

The output one get is below. The line 25 in ContentPanel.fxml is <Font size="16.0" />. It's as if the launcher doesn't set correctly the classpath, from there the PrismFontFactory cannot initialize.

$ /Applications/JavaFX\ Scene\ Builder\ 2.0.app/Contents/MacOS/JavaFX\ Scene\ Builder\ 2.0
java.lang.NullPointerException
file:/Applications/JavaFX%20Scene%20Builder%202.0.app/Contents/Java/SceneBuilderKit.jar!/com/oracle/javafx/scenebuilder/kit/editor/panel/content/ContentPanel.fxml:25
  at com.sun.javafx.font.PrismFontLoader.loadFont(PrismFontLoader.java:195)
  at javafx.scene.text.Font.<init>(Font.java:318)
  at com.sun.javafx.fxml.builder.JavaFXFontBuilder.build(JavaFXFontBuilder.java:75)
  at com.sun.javafx.fxml.builder.JavaFXFontBuilder.build(JavaFXFontBuilder.java:42)
  at javafx.fxml.FXMLLoader$ValueElement.processEndElement(FXMLLoader.java:743)
  at javafx.fxml.FXMLLoader.processEndElement(FXMLLoader.java:2688)
  at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2389)
  at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2283)
  at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractFxmlPanelController.makePanel(AbstractFxmlPanelController.java:58)
  at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractPanelController.getPanelRoot(AbstractPanelController.java:82)
  at com.oracle.javafx.scenebuilder.app.DocumentWindowController.controllerDidLoadFxml(DocumentWindowController.java:330)
  at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractFxmlWindowController.makeRoot(AbstractFxmlWindowController.java:65)
  at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractWindowController.getRoot(AbstractWindowController.java:41)
  at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractWindowController.getScene(AbstractWindowController.java:60)
  at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractWindowController.getStage(AbstractWindowController.java:82)
  at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractWindowController.openWindow(AbstractWindowController.java:96)
  at com.oracle.javafx.scenebuilder.app.SceneBuilderApp.start(SceneBuilderApp.java:103)
  at com.sun.javafx.application.LauncherImpl$5.run(LauncherImpl.java:811)
  at com.sun.javafx.application.PlatformImpl$7.run(PlatformImpl.java:331)
  at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:297)
  at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:294)
  at java.security.AccessController.doPrivileged(Native Method)
  at com.sun.javafx.application.PlatformImpl$6.run(PlatformImpl.java:294)
  at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)

loader.getController()=com.oracle.javafx.scenebuilder.kit.editor.panel.content.ContentPanelController@5a22f10
loader.getLocation()=jar:file:/Applications/JavaFX%20Scene%20Builder%202.0.app/Contents/Java/SceneBuilderKit.jar!/com/oracle/javafx/scenebuilder/kit/editor/panel/content/ContentPanel.fxml
loader.getController()=com.oracle.javafx.scenebuilder.app.DocumentWindowController@2cee161e
loader.getLocation()=jar:file:/Applications/JavaFX%20Scene%20Builder%202.0.app/Contents/Java/SceneBuilderApp.jar!/com/oracle/javafx/scenebuilder/app/DocumentWindow.fxml
Exception in Application start method
Workaround until RT-13281 is implemented: keep toolkit alive
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.javafx.main.Main.launchApp(Main.java:731)
at com.javafx.main.Main.main(Main.java:882)
Caused by: java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:868)
at com.sun.javafx.application.LauncherImpl.access$000(LauncherImpl.java:55)
at com.sun.javafx.application.LauncherImpl$1.run(LauncherImpl.java:157)
at java.lang.Thread.run(Thread.java:724)
Caused by: java.lang.RuntimeException: Failed to load file:/Applications/JavaFX%20Scene%20Builder%202.0.app/Contents/Java/SceneBuilderApp.jar!/com/oracle/javafx/scenebuilder/app/DocumentWindow.fxml
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractFxmlWindowController.makeRoot(AbstractFxmlWindowController.java:69)
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractWindowController.getRoot(AbstractWindowController.java:41)
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractWindowController.getScene(AbstractWindowController.java:60)
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractWindowController.getStage(AbstractWindowController.java:82)
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractWindowController.openWindow(AbstractWindowController.java:96)
at com.oracle.javafx.scenebuilder.app.SceneBuilderApp.start(SceneBuilderApp.java:103)
at com.sun.javafx.application.LauncherImpl$5.run(LauncherImpl.java:811)
at com.sun.javafx.application.PlatformImpl$7.run(PlatformImpl.java:331)
at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:297)
at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:294)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl$6.run(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
Caused by: java.lang.RuntimeException: Failed to load file:/Applications/JavaFX%20Scene%20Builder%202.0.app/Contents/Java/SceneBuilderKit.jar!/com/oracle/javafx/scenebuilder/kit/editor/panel/content/ContentPanel.fxml
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractFxmlPanelController.makePanel(AbstractFxmlPanelController.java:63)
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractPanelController.getPanelRoot(AbstractPanelController.java:82)
at com.oracle.javafx.scenebuilder.app.DocumentWindowController.controllerDidLoadFxml(DocumentWindowController.java:330)
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractFxmlWindowController.makeRoot(AbstractFxmlWindowController.java:65)
... 12 more
Caused by: java.lang.NullPointerException
at com.sun.javafx.font.PrismFontLoader.loadFont(PrismFontLoader.java:195)
at javafx.scene.text.Font.<init>(Font.java:318)
at com.sun.javafx.fxml.builder.JavaFXFontBuilder.build(JavaFXFontBuilder.java:75)
at com.sun.javafx.fxml.builder.JavaFXFontBuilder.build(JavaFXFontBuilder.java:42)
at javafx.fxml.FXMLLoader$ValueElement.processEndElement(FXMLLoader.java:743)
at javafx.fxml.FXMLLoader.processEndElement(FXMLLoader.java:2688)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2389)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2283)
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractFxmlPanelController.makePanel(AbstractFxmlPanelController.java:58)
... 15 more
Exception in thread "AppKit Thread" java.lang.NoClassDefFoundError: Could not initialize class com.sun.javafx.font.PrismFontFactory
at com.sun.javafx.font.PrismFontLoader.getSystemFontSize(PrismFontLoader.java:230)
at javafx.scene.text.Font.getDefaultSystemFontSize(Font.java:70)
at javafx.scene.text.Font.getDefault(Font.java:85)
at javafx.scene.CssStyleHelper.<clinit>(CssStyleHelper.java:1458)
at javafx.scene.Node.impl_processCSS(Node.java:8731)
at javafx.scene.Parent.impl_processCSS(Parent.java:1217)
at javafx.scene.Node.processCSS(Node.java:8637)
at javafx.scene.Node.impl_processCSS(Node.java:8682)
at com.oracle.javafx.scenebuilder.kit.metadata.util.Deprecation.processCSS(Deprecation.java:64)
at com.oracle.javafx.scenebuilder.app.preview.PreviewPanelController$1$1.run(PreviewPanelController.java:97)
at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:297)
at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:294)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl$6.run(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)