Session Management
Contains functions for managing progress bar sessions.
You do not need to start a new session in order to set the position of progress bars with the ProgressBar_SetPercentage or ProgressBar_AdvanceMilestone functions. However, when the progress bar is in marquee or auto mode, you must start a session for the progress bar to begin its motion.
When you start a session, the progress bar sets its position to 0, resets the current milestone, and establishes the initial timestamp against which the elapsed time of each milestone, and of the task as a whole, is measured.
Library: Progress Bar Control