Dygraph.prototype.renderGraph_ = function(is_initial_draw) {
this.plotter_.clear();
this.plotter_.render();
+
+ // TODO(danvk): is this a performance bottleneck when panning?
+ // The interaction canvas should already be empty in that situation.
this.canvas_.getContext('2d').clearRect(0, 0, this.canvas_.width,
this.canvas_.height);