- SDK: check for assetmanager when opening nifty files and do not open preview in case its not available

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@8530 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

sdk/jme3-gui/src/com/jme3/gde/gui/NiftyGuiDataObject.java

@@ -23,8 +23,8 @@ import org.openide.util.lookup.InstanceContent;
 import org.openide.util.lookup.ProxyLookup;
 
 public class NiftyGuiDataObject extends XmlMultiViewDataObject {
-    private static final int TYPE_TOOLBAR = 0;
 
+    private static final int TYPE_TOOLBAR = 0;
     protected final Lookup lookup;
     protected final InstanceContent lookupContents = new InstanceContent();
 
@@ -74,8 +74,13 @@ public class NiftyGuiDataObject extends XmlMultiViewDataObject {
 
     @Override
     protected DesignMultiViewDesc[] getMultiViewDesc() {
+        if (getLookup().lookup(ProjectAssetManager.class) == null) {
+            return new DesignMultiViewDesc[]{};
+        } else {
+
             return new DesignMultiViewDesc[]{new PreviewView(this, TYPE_TOOLBAR)};
         }
+    }
 
     @Override
     protected String getPrefixMark() {