ProgressMessageBox Is Not Updating - gwt

Question

In GXT (from Sencha) I am attempting to use a ProgressMessageBox to show the user that work is being done, but I am not seeing the message box until after all of the work is complete. Here is the code:
final ProgressMessageBox messageBox = new ProgressMessageBox("Task Description",
"Executing Task...");
messageBox.setProgressText("Calculating...");
messageBox.setPredefinedButtons();
messageBox.show();
for (int i = 0; i < 5; ++i) {
for (long l = 0l; l < 10000000000l; ++l) {
if (l == 12345l) {
MyUtil.info(60, "" + System.currentTimeMillis() / 1000);
}
}
messageBox.updateProgress((double)(i + 1) / 5, "{0}% Complete");
}
This code is in the SelectionHandler of a menu item. Obviously I am not actually just looping a few billion times in the "real" code, but when I perform the work that I want to execute I get the same result ... the message box is shown after all the work has been completed. I see the "info" messages (MyUtil#info is simply a wrapper around the GXT Info capability, which causes an info message to be displayed for the specified number of seconds) ... and on my machine, running the code shown, each message has a value that is about seven seconds greater than the previous message (but they all show up at the same time as the message box).
Is there something that I need to do after calling ProgressMessageBox#updateProgress to force the screen or message box to refresh?

Answer 1

I was able to get this to work by putting the task into a Scheduler#execute method. The example in the Sencha Explorer Demo uses a Timer, but since I don't know how long the execution will take I chose to use the Scheduler approach. Here is the relevant final code:
...
menuItem.addSelectionHandler(new SelectionHandler<Item>() {
#Override
public void onSelection(final SelectionEvent<Item> selectionEvent) {
final ProgressMessageBox messageBox = new ProgressMessageBox("Size All Columns", //
"Resizing Columns...");
messageBox.setProgressText("Calculating...");
// messageBox.setPredefinedButtons();
messageBox.show();
resizeNextColumn(messageBox,
_selectionModel instanceof CheckBoxSelectionModel ? 1 : 0,
_grid.getColumnModel().getColumnCount() - 1);
}
});
...
private void resizeNextColumn(final ProgressMessageBox messageBox,
final int columnIndex,
final int lastColumnIndex) {
Scheduler.get().scheduleDeferred(new ScheduledCommand() {
#Override
public void execute() {
resizeColumnToFit(columnIndex);
if (columnIndex == lastColumnIndex) {
messageBox.hide();
_grid.getView().refresh(true);
return;
}
messageBox.updateProgress((double)columnIndex / (lastColumnIndex + 1),
"{0}% Complete");
resizeNextColumn(messageBox, columnIndex + 1, lastColumnIndex);
}
});
}
One thing that didn't appear to work is the messageBox.setPredefinedButtons() call ... when I use this the progress bar in the message box doesn't update at all. I really didn't want an "OK" button on the dialog, but for now it'll have to do. I'm using 3.1.0 of GXT.