diff --git a/dev/api/getUserDefinedROIs.html b/dev/api/getUserDefinedROIs.html
index 5318f0eaa..caddfa04e 100644
--- a/dev/api/getUserDefinedROIs.html
+++ b/dev/api/getUserDefinedROIs.html
@@ -60,7 +60,7 @@ <h3>User defined ROIs:</h3>
 
                 const div = document.getElementById("user-defined-rois")
                 div.innerHTML = ""
-                
+
                 const list = document.createElement("ul")
                 div.appendChild(list)
 
diff --git a/dev/misc/custom-cursor-guide.html b/dev/api/setCustomCursorGuideMouseHandler.html
similarity index 77%
rename from dev/misc/custom-cursor-guide.html
rename to dev/api/setCustomCursorGuideMouseHandler.html
index 508690f40..a7276786d 100644
--- a/dev/misc/custom-cursor-guide.html
+++ b/dev/api/setCustomCursorGuideMouseHandler.html
@@ -20,7 +20,8 @@
 <script type="module">
 
     import igv from "../../js/index.js";
-    import {StringUtils} from "../node_modules/igv-utils/src/index.js";
+    import {StringUtils} from "../../node_modules/igv-utils/src/index.js";
+
     const numberFormatter = StringUtils.numberFormatter;
 
     let browser;
@@ -30,8 +31,8 @@
       const options =
             {
                 genome: "hg19",
-                locus: [ 'egfr', 'myc' ],
-                // locus: "myc",
+                // locus: [ 'egfr', 'myc' ],
+                locus: "myc",
                 showAllChromosomes: true,
                 showCursorTrackingGuide: true,
                 tracks:
@@ -47,8 +48,8 @@
 
         browser = await igv.createBrowser(document.getElementById('igvDiv'), options);
 
-        browser.setCustomCursorGuideMouseHandler(({bp, start, end, interpolant}) => {
-            console.log(`startBP ${ numberFormatter(start) } bp ${ numberFormatter(bp) } interpolant ${ interpolant.toFixed(3) } `);
+        browser.setCustomCursorGuideMouseHandler(({bp, interpolant}) => {
+            console.log(`base-pair ${ numberFormatter(bp) } interpolant ${ interpolant.toFixed(3) } `);
         });
 
     })();
diff --git a/js/rulerViewport.js b/js/rulerViewport.js
index cff0d620b..77517f25c 100644
--- a/js/rulerViewport.js
+++ b/js/rulerViewport.js
@@ -167,11 +167,11 @@ class RulerViewport extends TrackViewport {
 
             if (isWholeGenome) {
                 this.$tooltip.hide()
-                return
+                return undefined
             }
 
             const {x} = DOMUtils.translateMouseCoordinates(event, this.$viewport.get(0))
-            const {start, bpPerPixel} = this.referenceFrame
+            const {start, end, bpPerPixel} = this.referenceFrame
             const bp = Math.round(0.5 + start + Math.max(0, x) * bpPerPixel)
 
             this.$tooltipContent.text(StringUtils.numberFormatter(bp))
@@ -187,6 +187,7 @@ class RulerViewport extends TrackViewport {
                 if (this.$tooltip) this.$tooltip.hide()
             }, toolTipTimeout)
 
+            return { start, bp, end }
         }
 
     }