Bug 122687 Libraries dont appear to allow background colors on tables to be used
If I create a table and set the background color to blue in my library and then drag the table from the library to the report the background color does not go with it.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/DesignElement.java
assert child != null;
		assert child.getExtendsElement( ) == this;
		assert derived.contains( child );
		derived.remove( child );
	}
	/**
	 * Sets the parent element. This version should be used to implement a
	 * command to change the parent element. The caller must have validated that
	 * the new parent is valid for this element.
	 * <p>
	 * Part of: Inheritance system.
	 * 
	 * @param base
	 *            The new parent element, or null if the element is to have no
	 *            base element.
	 */
	public void setExtendsElement( DesignElement base )
	{
		DesignElement oldExtends = getExtendsElement( );
		if ( base == oldExtends )
			return;
		if ( oldExtends != null )
			oldExtends.dropDerived( this );
		if ( base == null )
		{
			extendsRef = null;
		}
		else
		{