Is there a GWT equivalent for SmartGWT's Live Grid with the Async loading of scrolled data?
Currently there's no sufficient equivalent for rich grids in GWT, let alone Ajax driven grid widgets.
One appropriate alternative would be GXT's live grid, but that's just going out of the frying pan into the fire, since you'd have to work with GXT instead of SmartGWT.
GWT was not meant to be used as a widget library, providing a vast selection of UI widgets, but merely supply a firm infrastructure for Java programmers to easily develop rich Ajax web applications. It can (and should) be extended with supplementary widget libraries to compensate for its lack thereof.