Theis typically used to display the progress of a long running operation. It provides a visual clue that processing is underway. The can be used in two different When an application can determine how much work needs to take place (e.g. read a fixed number of bytes from a file) and can monitor its progress, it can use the in percentage mode and the user sees a growing bar indicating the percentage of the work that has been completed. In this mode, the application is required to call gtk_progress_bar_set_fraction() periodically to update the progress bar. When an application has no accurate way of knowing the amount of work to do, it can use the in activity mode, which shows activity by a block moving back and forth within the progress area. In this mode, the application is required to call gtk_progress_bar_pulse() periodically to update the progress bar. There is quite a bit of flexibility provided to control the appearance of the . Functions are provided to control the orientation of the bar, optional text can be displayed along with the bar, and the step size used in activity mode can be set.