Fix #834. The select_bar bug was due to the barPlot being implicitly made into a global variable.
Fix #834. The select_bar bug was due to the barPlot being implicitly made
into a global variable.

alyssaq/plottable,NextTuesday/plottable,palantir/plottable,alyssaq/plottable,iobeam/plottable,softwords/plottable,NextTuesday/plottable,NextTuesday/plottable,palantir/plottable,palantir/plottable,jacqt/plottable,onaio/plottable,RobertoMalatesta/plottable,gdseller/plottable,RobertoMalatesta/plottable,palantir/plottable,softwords/plottable,danmane/plottable,gdseller/plottable,onaio/plottable,danmane/plottable,iobeam/plottable,jacqt/plottable,RobertoMalatesta/plottable,jacqt/plottable,gdseller/plottable,danmane/plottable,softwords/plottable,iobeam/plottable,onaio/plottable,alyssaq/plottable