Hi there,
Try this:
google.maps.event.addDomListener(drawingManager, 'rectanglecomplete', function(rectangle) {
document.getElementById("savedata").value =rectangle.getBounds();
drawingManager.setOptions({
drawingControl: false
});
drawingManager.setDrawingMode(null);
var rectangle = rectangle.overlay;
google.maps.event.addListener(rectangle, "bounds_changed", function(event) {
document.getElementById("savedata").value = rectangle.getBounds();
});
});