Uses addLineWidget in the debugger.html CodeMirror editor

addLineWidget.patch

diff --git a/public/js/components/Editor.css b/public/js/components/Editor.css
index ff6160c..3986f92 100644
--- a/public/js/components/Editor.css
+++ b/public/js/components/Editor.css
@@ -52,6 +52,10 @@
   z-index: 0;
 }
 
+.new-breakpoint .CodeMirror-linewidget .helpful-message {
+  background-color: yellow;
+}
+
 .debug-line .CodeMirror-line {
   background-color: var(--breakpoint-active-color) !important;
 }
diff --git a/public/js/components/EditorBreakpoint.js b/public/js/components/EditorBreakpoint.js
index 750b289..ea4bc68 100644
--- a/public/js/components/EditorBreakpoint.js
+++ b/public/js/components/EditorBreakpoint.js
@@ -39,6 +39,10 @@ const Breakpoint = React.createClass({
       makeMarker(bp.disabled)
     );
     this.props.editor.addLineClass(line, "line", "new-breakpoint");
+    let node = document.createElement("div");
+    node.textContent = "This is the helpful message below a breakpoint";
+    node.className = "helpful-message";
+    this.props.editor.addLineWidget(line, node, { });
   },
 
   shouldComponentUpdate(nextProps) {