This toolbar lets you navigate along the time dimension of the piece. This bar is somewhat similar to the controls found in most software sequencers. Note that using the bottom zoomSlider at the bottom of the piece is a most straightforward way to achieve the same result and it occupies less screen estate.
Group: Indicates and lets you change the group offset in the current piece. Groups are groups of bars, defined by the time scale.
Bar: Indicates and lets you change the bar offset in the current piece. Bars are defined as a group of beats, defined in the time scale.
Beat: Indicates and lets you change the beat offset in the current piece. Bars are defined as a group of beats, defined in the time scale.
Zoom: Indicates and lets you control how many units you want displayed at a time.
Zoom unit: This combo box lets you specify in what units you want the zoom level to define: groups (overview), bars or beats (zoom in).