Continuing the discussion from Circles on cyclinders:
Yes it’s a custom bar. I have customised the Measurement toolbar. You can make your own by opening the toolbar dialog and creating a new one or changing an existing one.
You can drag and drop tools from any Native toolbar. Use ctrl when you drag to drag a copy to the new bar rather than drag the original off. If you happen to mess up a toolbar by dragging something off and you want it back, just select the toolbar in the dialog and hit the reset button.