Bug 165278 this.getDisplayContent()="" in script of text will destroy preview[0801]
Description: this.getDisplayContent()="" in script of text will destroy preview Build number:2.1.2.v20061120 and 2.2.0.v20061117 Steps to reproduce: 1. Insert a text item, select it and switch to script editor 2. Input this.getDisplayContent()="" and preview Expected result: Error message about the incorrect script. Actual result: In 2.1.2, I saw HTTP Status 500 - type Exception report message description The server encountered an internal error () that prevented it from fulfilling this request. In 2.2.0, I saw error dialog with java.lang.ClassCastException.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/executor/ExecutionContext.java
}
		}
	}
	public void registerGlobalBean( String name, Serializable value )
	{
		persistentBeans.put( name, value );
		registerInRoot( name, value );
	}
	public void unregisterGlobalBean( String name )
	{
		persistentBeans.remove( name );
		registerInRoot( name, null );
	}
	public Map getGlobalBeans( )
	{
		return persistentBeans;
	}
	private void registerInRoot( String name, Object value )
	{
		Scriptable root = scriptContext.getRootScope( );
		Object sObj = Context.javaToJS( value, root );
		root.put( name, root, sObj );
	}
	/**
	 * Evaluate a BIRT expression
	 * 
	 * @param source
	 *            the expression to be evaluated
	 * @return the result if no error exists, otherwise null.
	 *