This simple demo shows how to attatch waitbar in GUI and displays other informaton like estimated time, elapsed time and percentage completed.
Another demo within this GUI is a simple fun for testing your speed of mouse click on moving button in the GUI figure. You can change the speed of button movement by slider in the GUI. When you able to click the moving button which has caption 'Stop me', then it stops moving of this button and waitbar and also gives your score between 0 (worst) and 100 (best).

The GUI also counts how many movements are in the left and right panels of the GUI. In total 100 movements, half of them should be in left panel.