tooltip.getCellFormatter().setStyleName(2, 0, "bottomLeft");
tooltip.getCellFormatter().setStyleName(2, 1, "bottomMiddle");
tooltip.getCellFormatter().setStyleName(2, 2, "bottomRight");
HTML content = new HTML(
"<span class=date>"+formatter.format(new Date(time))+"</span> <br/>"+
"<span class=text>"+description+"</span>"
);
tooltip.setWidget(1, 1, content);