// Attach a DrawingArea inside the clipping area (used for vector rendering):
drawingArea = new DrawingArea(100, 100);
add(drawingArea, 0, 0);
// First child within the vector drawing area is a group for the map to render it's non-HTML layers:
layerVectorContainer = new VectorGroup();
drawingArea.add(layerVectorContainer);
// Second child within the vector drawing area is a group for screen and world containers:
userVectorContainer = new VectorGroup();
drawingArea.add(userVectorContainer);
// Third child within the vector drawing area is a group for map gadget containers:
gadgetVectorContainer = new VectorGroup();
drawingArea.add(gadgetVectorContainer);
// Firefox and Chrome allow for DnD of images. This default behavior is not wanted.
addMouseDownHandler(new MouseDownHandler() {