The toolbar contains useful buttons to manage the visualisation of the timelines:
Refresh: Refresh the timelines manually.
Collapse/Expand: Shrinks or widens all the groups of timelines in the main view. This action can also be done for a single database by clicking on its friendly name (see 82.1.1.0 Database settings chapter for reference).
Zoom in/out: Allows for magnifying or reducing the timeline view.
Fit to margin: Fits the whole timeline length in the window, restoring the default view.