--- a/devtools/server/actors/highlighters/shapes.js
+++ b/devtools/server/actors/highlighters/shapes.js
@@ -836,18 +836,17 @@ class ShapesHighlighter extends AutoRefr
       let [newX, newY] = apply(this.transformMatrix, vector);
       let precisionX = getDecimalPrecision(unitX);
       let precisionY = getDecimalPrecision(unitY);
       newX = (newX * ratioX).toFixed(precisionX);
       newY = (newY * ratioY).toFixed(precisionY);
 
       return `${newX}${unitX} ${newY}${unitY}`;
     }).join(", ");
-    polygonDef = (this.geometryBox) ? `polygon(${polygonDef}) ${this.geometryBox}` :
-                                      `polygon(${polygonDef})`;
+    polygonDef = `polygon(${polygonDef}) ${this.geometryBox}`.trim();
 
     this.currentNode.style.setProperty(this.property, polygonDef, "important");
   }
 
   /**
    * Transform a circle depending on the current transformation matrix.
    * @param {Number} transX the number of pixels the shape is translated on the x axis
    *                 before scaling
@@ -860,21 +859,19 @@ class ShapesHighlighter extends AutoRefr
     let [newCx, newCy] = apply(this.transformMatrix, [valueX / ratioX, valueY / ratioY]);
     if (transX !== null) {
       // As part of scaling, the shape is translated to be tangent to the line y=0.
       // To get the new radius, we translate the new cx back to that point and get
       // the distance to the line y=0.
       radius = `${Math.abs((newCx - transX) * ratioRad)}${unitRad}`;
     }
 
-    let circleDef = (this.geometryBox) ?
-      `circle(${radius} at ${newCx * ratioX}${unitX} ` +
-        `${newCy * ratioY}${unitY} ${this.geometryBox}` :
-      `circle(${radius} at ${newCx * ratioX}${unitX} ${newCy * ratioY}${unitY}`;
-    this.currentNode.style.setProperty(this.property, circleDef, "important");
+    let circleDef = `circle(${radius} at ${newCx * ratioX}${unitX} ` +
+        `${newCy * ratioY}${unitY}) ${this.geometryBox}`.trim();
+    this.emit("highlighter-event", { type: "shape-change", value: circleDef });
   }
 
   /**
    * Transform an ellipse depending on the current transformation matrix.
    * @param {Number} transX the number of pixels the shape is translated on the x axis
    *                 before scaling
    * @param {Number} transY the number of pixels the shape is translated on the y axis
    *                 before scaling
@@ -888,22 +885,19 @@ class ShapesHighlighter extends AutoRefr
     if (transX !== null && transY !== null) {
       // As part of scaling, the shape is translated to be tangent to the lines y=0 & x=0.
       // To get the new radii, we translate the new center back to that point and get the
       // distances to the line x=0 and y=0.
       rx = `${Math.abs((newCx - transX) * ratioRX)}${unitRX}`;
       ry = `${Math.abs((newCy - transY) * ratioRY)}${unitRY}`;
     }
 
-    let ellipseDef = (this.geometryBox) ?
-        `ellipse(${rx} ${ry} at ${newCx * ratioX}${unitX} ` +
-          `${newCy * ratioY}${unitY}) ${this.geometryBox}` :
-        `ellipse(${rx} ${ry} at ${newCx * ratioX}${unitX} ` +
-          `${newCy * ratioY}${unitY})`;
-    this.currentNode.style.setProperty(this.property, ellipseDef, "important");
+    let ellipseDef = `ellipse(${rx} ${ry} at ${newCx * ratioX}${unitX} ` +
+          `${newCy * ratioY}${unitY}) ${this.geometryBox}`.trim();
+    this.emit("highlighter-event", { type: "shape-change", value: ellipseDef });
   }
 
   /**
    * Transform an inset depending on the current transformation matrix.
    */
   _transformInset() {
     let { top, left, right, bottom } = this[_dragging].pointsInfo;
     let { width, height } = this.currentDimensions;
@@ -975,18 +969,17 @@ class ShapesHighlighter extends AutoRefr
     let newX = (valueX + deltaX).toFixed(precisionX);
     let newY = (valueY + deltaY).toFixed(precisionY);
 
     let polygonDef = (this.fillRule) ? `${this.fillRule}, ` : "";
     polygonDef += this.coordUnits.map((coords, i) => {
       return (i === point) ?
         `${newX}${unitX} ${newY}${unitY}` : `${coords[0]} ${coords[1]}`;
     }).join(", ");
-    polygonDef = (this.geometryBox) ? `polygon(${polygonDef}) ${this.geometryBox}` :
-                                      `polygon(${polygonDef})`;
+    polygonDef = `polygon(${polygonDef}) ${this.geometryBox}`.trim();
 
     this.currentNode.style.setProperty(this.property, polygonDef, "important");
   }
 
   /**
    * Set the inline style of the polygon, adding a new point.
    * TODO: Bug 1436054 - Do not default to percentage unit when inserting new point.
    * https://bugzilla.mozilla.org/show_bug.cgi?id=1436054
@@ -996,18 +989,17 @@ class ShapesHighlighter extends AutoRefr
    * @param {Number} y the y coordinate of the new point
    */
   _addPolygonPoint(after, x, y) {
     let polygonDef = (this.fillRule) ? `${this.fillRule}, ` : "";
     polygonDef += this.coordUnits.map((coords, i) => {
       return (i === after) ? `${coords[0]} ${coords[1]}, ${x}% ${y}%` :
                              `${coords[0]} ${coords[1]}`;
     }).join(", ");
-    polygonDef = (this.geometryBox) ? `polygon(${polygonDef}) ${this.geometryBox}` :
-                                      `polygon(${polygonDef})`;
+    polygonDef = `polygon(${polygonDef}) ${this.geometryBox}`.trim();
 
     this.hoveredPoint = after + 1;
     this._emitHoverEvent(this.hoveredPoint);
     this.currentNode.style.setProperty(this.property, polygonDef, "important");
   }
 
   /**
    * Set the inline style of the polygon, deleting the given point.
@@ -1015,18 +1007,17 @@ class ShapesHighlighter extends AutoRefr
    */
   _deletePolygonPoint(point) {
     let coordinates = this.coordUnits.slice();
     coordinates.splice(point, 1);
     let polygonDef = (this.fillRule) ? `${this.fillRule}, ` : "";
     polygonDef += coordinates.map((coords, i) => {
       return `${coords[0]} ${coords[1]}`;
     }).join(", ");
-    polygonDef = (this.geometryBox) ? `polygon(${polygonDef}) ${this.geometryBox}` :
-                                      `polygon(${polygonDef})`;
+    polygonDef = `polygon(${polygonDef}) ${this.geometryBox}`.trim();
 
     this.hoveredPoint = null;
     this._emitHoverEvent(this.hoveredPoint);
     this.currentNode.style.setProperty(this.property, polygonDef, "important");
   }
   /**
    * Handle a click when highlighting a circle.
    * @param {Number} pageX the x coordinate of the click
@@ -1081,34 +1072,31 @@ class ShapesHighlighter extends AutoRefr
     let { radius, cx, cy } = this.coordUnits;
 
     if (point === "center") {
       let { unitX, unitY, valueX, valueY, ratioX, ratioY, x, y} = this[_dragging];
       let deltaX = (pageX - x) * ratioX;
       let deltaY = (pageY - y) * ratioY;
       let newCx = `${valueX + deltaX}${unitX}`;
       let newCy = `${valueY + deltaY}${unitY}`;
-      let circleDef = (this.geometryBox) ?
-            `circle(${radius} at ${newCx} ${newCy}) ${this.geometryBox}` :
-            `circle(${radius} at ${newCx} ${newCy})`;
+      // if not defined by the user, geometryBox will be an empty string; trim() cleans up
+      let circleDef = `circle(${radius} at ${newCx} ${newCy}) ${this.geometryBox}`.trim();
 
       this.currentNode.style.setProperty(this.property, circleDef, "important");
     } else if (point === "radius") {
       let { value, unit, origRadius, ratio } = this[_dragging];
       // convert center point to px, then get distance between center and mouse.
       let { x: pageCx, y: pageCy } = this.convertPercentToPageCoords(this.coordinates.cx,
                                                                      this.coordinates.cy);
       let newRadiusPx = getDistance(pageCx, pageCy, pageX, pageY);
 
       let delta = (newRadiusPx - origRadius) * ratio;
       let newRadius = `${value + delta}${unit}`;
 
-      let circleDef = (this.geometryBox) ?
-                      `circle(${newRadius} at ${cx} ${cy} ${this.geometryBox}` :
-                      `circle(${newRadius} at ${cx} ${cy}`;
+      let circleDef = `circle(${newRadius} at ${cx} ${cy}) ${this.geometryBox}`.trim();
 
       this.currentNode.style.setProperty(this.property, circleDef, "important");
     }
   }
 
   /**
    * Handle a click when highlighting an ellipse.
    * @param {Number} pageX the x coordinate of the click
@@ -1172,43 +1160,40 @@ class ShapesHighlighter extends AutoRefr
     let { rx, ry, cx, cy } = this.coordUnits;
 
     if (point === "center") {
       let { unitX, unitY, valueX, valueY, ratioX, ratioY, x, y} = this[_dragging];
       let deltaX = (pageX - x) * ratioX;
       let deltaY = (pageY - y) * ratioY;
       let newCx = `${valueX + deltaX}${unitX}`;
       let newCy = `${valueY + deltaY}${unitY}`;
-      let ellipseDef = (this.geometryBox) ?
-        `ellipse(${rx} ${ry} at ${newCx} ${newCy}) ${this.geometryBox}` :
-        `ellipse(${rx} ${ry} at ${newCx} ${newCy})`;
+      let ellipseDef =
+        `ellipse(${rx} ${ry} at ${newCx} ${newCy}) ${this.geometryBox}`.trim();
 
       this.currentNode.style.setProperty(this.property, ellipseDef, "important");
     } else if (point === "rx") {
       let { value, unit, origRadius, ratio } = this[_dragging];
       let newRadiusPercent = Math.abs(percentX - this.coordinates.cx);
       let { width } = this.currentDimensions;
       let delta = ((newRadiusPercent / 100 * width) - origRadius) * ratio;
       let newRadius = `${value + delta}${unit}`;
 
-      let ellipseDef = (this.geometryBox) ?
-        `ellipse(${newRadius} ${ry} at ${cx} ${cy}) ${this.geometryBox}` :
-        `ellipse(${newRadius} ${ry} at ${cx} ${cy})`;
+      let ellipseDef =
+        `ellipse(${newRadius} ${ry} at ${cx} ${cy}) ${this.geometryBox}`.trim();
 
       this.currentNode.style.setProperty(this.property, ellipseDef, "important");
     } else if (point === "ry") {
       let { value, unit, origRadius, ratio } = this[_dragging];
       let newRadiusPercent = Math.abs(percentY - this.coordinates.cy);
       let { height } = this.currentDimensions;
       let delta = ((newRadiusPercent / 100 * height) - origRadius) * ratio;
       let newRadius = `${value + delta}${unit}`;
 
-      let ellipseDef = (this.geometryBox) ?
-        `ellipse(${rx} ${newRadius} at ${cx} ${cy}) ${this.geometryBox}` :
-        `ellipse(${rx} ${newRadius} at ${cx} ${cy})`;
+      let ellipseDef =
+        `ellipse(${rx} ${newRadius} at ${cx} ${cy}) ${this.geometryBox}`.trim();
 
       this.currentNode.style.setProperty(this.property, ellipseDef, "important");
     }
   }
 
   /**
    * Handle a click when highlighting an inset.
    * @param {Number} pageX the x coordinate of the click

--- a/devtools/server/actors/utils/shapes-utils.js
+++ b/devtools/server/actors/utils/shapes-utils.js
@@ -4,17 +4,17 @@
  * Get the distance between two points on a plane.
  * @param {Number} x1 the x coord of the first point
  * @param {Number} y1 the y coord of the first point
  * @param {Number} x2 the x coord of the second point
  * @param {Number} y2 the y coord of the second point
  * @returns {Number} the distance between the two points
  */
 const getDistance = (x1, y1, x2, y2) => {
-  return Math.hypot(x2 - x1, y2 - y1);
+  return Math.round(Math.hypot(x2 - x1, y2 - y1));
 };
 
 /**
  * Determine if the given x/y coords are along the edge of the given ellipse.
  * We allow for a small area around the edge that still counts as being on the edge.
  * @param {Number} x the x coordinate of the click
  * @param {Number} y the y coordinate of the click
  * @param {Number} cx the x coordinate of the center of the ellipse