Jake,
Sure in the Widget.js file there is the _initLayer function. in that function you will find:
Add line 4 and adjust to suit your needs.
if (this.summaryDisplayEnabled) {
this.lyrSummary = new GraphicsLayer();
this.lyrSummary.setVisibility(false);
this.lyrSummary.setOpacity(0.5);
this.map.addLayer(this.lyrSummary);
}