From Xojo Documentation
Adds a rotating progress wheel to a window.
Use the Visible property of the control to show or hide it. When it is visible, it is animated automatically.
Animation requires that the application is able to refresh the control. This will happen while the application is idle. If the control is to be animated during a tight loop, this can be achieved by putting the loop in a Thread, or via the RectControl.Refresh method.
The ProgressWheel is always displayed at the standard system size. Resizing it has no effect.