QTL Ontology colour : QTL with no .Ontology is black, make it translu…

…cent.

 ... to avoid obscuring those QTLs which do have .Ontology
feature.js : add ontologyColourDefault = #3, use in ontologyColour() when no values.Ontology.

frontend/app/models/feature.js

@@ -12,6 +12,12 @@ import { traitColour } from '../utils/draw/axis';
 
 const dLog = console.debug;
 
+/** many QTLs don't have .Ontology yet (so colour is undefined - black) and
+ * they are obscuring those that do, so try making the black translucent.
+ */
+const ontologyColourDefault = "#0003";
+
+
 export default Model.extend({
   ontology : service('data/ontology'),
 
@@ -78,7 +84,8 @@ export default Model.extend({
   get ontologyColour() {
   // return ontology_colour_scale(ontologyId);
   let ontologyId = this.get('values.Ontology'),
-      colour = ontologyId && this.get('ontology').qtlColour(ontologyId);
+      colour = ontologyId ? this.get('ontology').qtlColour(ontologyId) :
+      ontologyColourDefault;
   return colour;
   },