title: Theme detection in project properties fails after theme save in GUI Builder
body: <p>I have been working with GUI Builder in NetBeans and now when I save any changes in the theme, project properties do not show the theme selected. Anytime I do git reset --hard and check project properties, the theme resource file is selected. Any help?</p>
  
  <p>Hello, 
  The exception below shows when I click on save in the GUI Builder even without changing anything in there. The resource and main form entry in project properties are blank. codenameone_settings.properties entries are correct for 
  guiResource=theme.res
  mainForm=Main
  libraries are up to date</p>
  
  <p>``  java.lang.ArrayIndexOutOfBoundsException: 0
      at com.codename1.ui.util.Resources.readMultiImage(Resources.java:1083)
      at com.codename1.ui.util.Resources.readMultiImage(Resources.java:1056)
      at com.codename1.ui.util.Resources.createImage(Resources.java:1038)
      at com.codename1.ui.util.Resources.createImage(Resources.java:948)
      at com.codename1.ui.util.Resources.openFileImpl(Resources.java:296)
      at com.codename1.ui.util.Resources.openFile(Resources.java:260)
      at com.codename1.ui.util.Resources.(Resources.java:181)
      at com.codename1.ui.util.Resources.open(Resources.java:751)
      at com.codename1.ui.util.Resources.open(Resources.java:675)
      [catch] at com.codename1.CodeName1CustomizerTab.createCategory(CodeName1CustomizerTab.java:203)
      at    org.netbeans.spi.project.ui.support.ProjectCustomizer$DelegateCategoryProvider.readCategories(ProjectCustomizer.java:672)
      at org.netbeans.spi.project.ui.support.ProjectCustomizer$DelegateCategoryProvider.getSubCategories(ProjectCustomizer.java:633)
      at org.netbeans.spi.project.ui.support.ProjectCustomizer.createCustomizerDialog(ProjectCustomizer.java:260)
      at org.netbeans.modules.java.j2seproject.ui.customizer.CustomizerProviderImpl.showCustomizer(CustomizerProviderImpl.java:131)
      at org.netbeans.modules.java.j2seproject.ui.customizer.CustomizerProviderImpl.showCustomizer(CustomizerProviderImpl.java:108)
      at org.netbeans.modules.java.j2seproject.ui.customizer.CustomizerProviderImpl.showCustomizer(CustomizerProviderImpl.java:103)
      at org.netbeans.modules.project.ui.actions.CustomizeProject$1$1.run(CustomizeProject.java:160)
      at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
      at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:744)
      at java.awt.EventQueue.access$400(EventQueue.java:97)
      at java.awt.EventQueue$3.run(EventQueue.java:697)
      at java.awt.EventQueue$3.run(EventQueue.java:691)
      at java.security.AccessController.doPrivileged(Native Method)
      at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
      at java.awt.EventQueue.dispatchEvent(EventQueue.java:714)
      at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159)
      at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
      at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
      at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
      at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
      at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
      at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)</p>