GXT as is the case with all toolkits, has a good collection of UI components.
But these components cannot to used out of the box to solve your problems.
One such is the progress bar in the GXT, when I felt a need to use the progress bar to indicate the progress of the operation being performed,
I quickly googled and found some interesting examples . But it involved calculating the amount of work remaining/done to update the progress.
So I wrote this little extension of the progress bar, which I call Continuos Progress bar, it works pretty much like the Windows Vista progress indicator (unlike Ubuntu’s).
Code is small and self explanatory, so I dont want to bother myself explaining the code, and rather save myself time to catch some sleep 
Code included here is distributed under Apache v2.0 license, so you can freely modifiy, distribute or make commercial use of the code.
class ContinousProgressBar extends ProgressBar {
private boolean stopProgress = true;
private Timer timer;
public ContinousProgressBar() {
setBounds(10, 10, 200, Style.DEFAULT);
timer = new Timer() {
int counter = 0;
@Override
public void run() {
if (stopProgress) {
updateProgress(10.0, "");
return;
}
if (counter == 10) {
counter = 0;
}
counter++;
updateProgress(counter / 10.0, "");
this.schedule(100);
}
};
}
public void start() {
if (stopProgress) {
timer.schedule(100);
stopProgress = false;
}
}
public void stop() {
stopProgress = true;
}
}
This is how it can be used with start/stop button. Below is a sample EntryPoint for the GWT demonstrating the thing.
public class ContinousProgressDemo implements EntryPoint {
private boolean stopProgress = true;
public void onModuleLoad2() {
ContentPanel cp = new ContentPanel();
cp.setSize(200, 100);
final ProgressBar bar = new ProgressBar();
bar.setBounds(10, 10, 200, Style.DEFAULT);
final Timer timer = new Timer() {
int val = 0;
@Override
public void run() {
if (stopProgress) {
bar.updateProgress(10.0, "");
return;
}
if (val == 10) {
val = 0;
}
val++;
bar.updateProgress(val / 10.0, "");
this.schedule(100);
}
};
cp.add(bar);
final ToggleButton toggle = new ToggleButton("Start/Stop");
toggle.addListener(Events.Toggle, new Listener<ButtonEvent>() {
@Override
public void handleEvent(ButtonEvent be) {
boolean oldState = stopProgress;
stopProgress = !toggle.isPressed();
if (oldState && !stopProgress) {
timer.schedule(100);
}
}
});
toggle.toggle(false);
cp.getButtonBar().add(toggle);
RootPanel.get().add(cp);
}
@Override
public void onModuleLoad() {
final ContinousProgressBar contProgress = new ContinousProgressBar();
final ToggleButton toggle = new ToggleButton("Start");
toggle.addListener(Events.Toggle, new Listener<ButtonEvent>() {
@Override
public void handleEvent(ButtonEvent be) {
if (toggle.isPressed()) {
toggle.setText("Stop");
contProgress.start();
} else {
toggle.setText("Start");
contProgress.stop();
}
}
});
toggle.toggle(false);
ContentPanel cp = new ContentPanel();
cp.setHeading("Continuos progressbar");
cp.setSize(200, 100);
cp.setFrame(true);
cp.add(contProgress);
cp.getButtonBar().add(toggle);
RootPanel.get().add(cp);
}
}
