Bug 142137 Style name can't be changed to None in Property Editor after delete the style
Steps to reproduce: 1.New a style named "S1", apply it on a label 2.Delete "S1" 3.Switch to Property Editor, change label style to None Expected result: Style is changed to None Actual result: Style is still "S1" till change it with context menu
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/StyleCommand.java
name = style.getName( );
		setStyle( name );
	}
	/**
	 * Sets the extends attribute for an element given the new parent element.
	 * 
	 * @param parent
	 *            the new parent element.
	 * @throws StyleException
	 *             if the element can not be extended or the base element is not
	 *             on component slot, or the base element has no name.
	 */
	public void setStyleElement( StyleHandle parent ) throws StyleException
	{
		if ( parent == null )
		{
			setStyle( null );
			return;
		}
		setStyle( parent.getName( ) );
	}
	/**
	 * Sets the theme with the given element reference value. Call this method
	 * when the theme name or theme element has been validated. Otherwise, uses
	 * {@link #setStyle(String)} or {@link #setStyleElement(Theme)}.
	 * 
	 * @param refValue
	 *            the validated reference value
	 * @throws StyleException
	 *             if the style is not found.