public void setScale(double scale) {
		if(scale <= 0) {
			scale = 1;
		}
		this.scale = scale;
		updatePreferredSize();
	}
Get an adaptor for root that indicates how to walk ANTLR trees.
 Override to change the adapter from the default of {@link TreeLayoutAdaptor}
tool/src/org/antlr/v4/gui/TreeViewer.java