// Create an area to echo position information.
final HTML echo = new HTML();
// Create a target box to test inside
final Label sandbox = new Label();
sandbox.sinkEvents(Event.ONMOUSEMOVE);
sandbox.setPixelSize(300, 300);
sandbox.getElement().getStyle().setProperty("border", "3px solid blue");
sandbox.getElement().getStyle().setProperty("cursor", "crosshair");
// Keep the crosshair under the cursor