OO-321: only show 1 button group next/previous if there isn't any scorm content to show

src/main/java/org/olat/core/gui/render/velocity/VelocityRenderDecorator.java

@@ -560,6 +560,16 @@ public class VelocityRenderDecorator {
 		Component source = renderer.findComponent(componentName);
 		return (source != null);
 	}
+	
+	/**
+	 * @param componentName
+	 * @return true if the component with name componentName is a child of the current container and if this
+	 * component is visible
+	 */
+	public boolean visible(String componentName) {
+		Component source = renderer.findComponent(componentName);
+		return (source != null && source.isVisible());
+	}
 
 	/**
 	 * returns an object from the context of velocity

src/main/java/org/olat/modules/scorm/OLATApiAdapter.java

@@ -96,7 +96,9 @@ public	class OLATApiAdapter extends LogDelegator implements ch.ethz.pfplms.scorm
 	}
 	
 	public void addAPIListener(ScormAPICallback apiCallback) {
-		apiCallbacks.add(apiCallback);
+		if(apiCallback != null) {
+			apiCallbacks.add(apiCallback);
+		}
 	}
 
 	/**

src/main/java/org/olat/modules/scorm/ScormAPIandDisplayController.java

@@ -319,6 +319,7 @@ public class ScormAPIandDisplayController extends MainLayoutBasicController {
 
 		if (te.getCommand().equals(MenuTree.COMMAND_TREENODE_EXPANDED)) {
 			iframectr.getInitialComponent().setVisible(false);
+			myContent.setDirty(true);//update the view
 		} else {
 			iframectr.getInitialComponent().setVisible(true);
 			String scormId = String.valueOf(treeModel.lookupScormNodeId(tn));

src/main/java/org/olat/modules/scorm/_content/display.html

@@ -18,7 +18,7 @@
 		//todo:gs:c On some sco's the first attempt to call the RTE fails, sending a dummy call is a workaroud for this
 		passApiCall("initcall","empty","empty");
 	</script>
-	
+
 	#if($showNavButtons)
 	<div class="o_scorm_navigation" >
 		$r.render("previousScoTop")
@@ -28,7 +28,7 @@
 	<div class="o_scorm_content">
 		$r.render("contentpackage")
 	</div>
-	#if($showNavButtons)
+	#if($showNavButtons && $r.visible("contentpackage"))
 	<div class="o_scorm_navigation" >
 		$r.render("previousScoBottom")
 		$r.render("nextScoBottom")