GWT: How to center element containing CellTable? - gwt

Question

I'm trying to center an element that contains a CellTable. The actual
centering logic works okay, but I'm having problems with all those
attaching/detaching events. Basically, I'm doing this in my container
widget:
#Override
public void onLoad() {
super.onLoad();
center();
}
However, it seems that onLoad on the container does not mean that all
children have loaded, so... the actual centering routine is called too
early and Element.getOffsetWidth/getOffsetHeight are both returning 0.
This results in the container being displayed with the left upper corner
in the center of the screen.
Same thing happens if I use an AttachEvent.Handler on the CellTable.
So... is there any event on CellTable, or on Widget or whatever that
allows me to trigger an action when the DOM subtree has been attached to
the DOM?
Thanks in advance.

Answer 1

Take a look at scheduleDeferred. A deferred command is executed after the browser event loop returns.
Scheduler.get().scheduleDeferred(new ScheduledCommand() {
#Override
public void execute() {
center();
}
});

Answer 2

Override onAttach instead of onLoad. onAttach default implementation calls onLoad followed by doAttachChildren (which calls onAttach on each child widget), so the following code should call center after the children have been attached:
#Override
public void onAttach() {
super.onAttach();
center();
}
(BTW, the default implementation of onLoad is a no-op)