From a widget's actions menu you can:
View Table or View Chart: switch between the chart and the numbers behind it.
Fullscreen: open the widget on its own. Exit Fullscreen returns to the dashboard.
Stack series or Unstack series, Show as line or Show as bars: change how a chart is drawn. Restore original undoes your changes.
Show details: see the Metrics in Widget and Filters in Widget.
To drill down, select a point or a bar on the chart. The widget shows the level of detail below it. Select Drill up to go back.
[Image: A chart widget's actions menu, and a drilled-down chart with the "Drill up" control]
These changes only affect your view. Nobody else's dashboard changes.