Brush through the datapoints by drawing a rectangle anywhere on the chart. You can reset the brush by clicking anywhere on the chart. To clear out the selection column on the right, press 'clear selection'.
You can highlight datapoints in any category by clicking the legends below the chart. Reset the highlight by double-clicking on the legends or anywhere near them. The legends represent the categories of the datapoints above the significance line.
Inspect your own selection by drawing a rectangle anywhere on the chart and press enter.
Mark interesting data points by clicking them and move the label around by dragging it. Reset the labels by double-clicking any of the points.