StringBuffer mouseOutBuffer = previousOnMouseOut == null?
new StringBuffer(): new StringBuffer(previousOnMouseOut);
final HoverStylePropertyIteratee iteratee =
new HoverStylePropertyIteratee(mouseOverBuffer,
mouseOutBuffer);
hoverProperties.iteratePropertyValues(iteratee);
// emulate onmouseover styles (those when hovering).
element.setAttribute(ON_MOUSE_OVER, mouseOverBuffer.toString());
// emulate onmouseout styles (those when not hovering).
element.setAttribute(ON_MOUSE_OUT, mouseOutBuffer.toString());
}