--- a/dom/events/test/pointerevents/mochitest.ini
+++ b/dom/events/test/pointerevents/mochitest.ini
@@ -77,17 +77,16 @@ support-files =
 [test_pointerevent_releasepointercapture_onpointerup_mouse-manual.html]
   support-files = pointerevent_releasepointercapture_onpointerup_mouse-manual.html
 [test_pointerevent_releasepointercapture_release_right_after_capture-manual.html]
   support-files = pointerevent_releasepointercapture_release_right_after_capture-manual.html
 [test_pointerevent_setpointercapture_disconnected-manual.html]
   support-files = pointerevent_setpointercapture_disconnected-manual.html
 [test_pointerevent_setpointercapture_inactive_button_mouse-manual.html]
   support-files = pointerevent_setpointercapture_inactive_button_mouse-manual.html
-  disabled = should be investigated
 [test_pointerevent_setpointercapture_invalid_pointerid-manual.html]
   support-files = pointerevent_setpointercapture_invalid_pointerid-manual.html
 [test_pointerevent_setpointercapture_override_pending_capture_element-manual.html]
   support-files = pointerevent_setpointercapture_override_pending_capture_element-manual.html
 [test_pointerevent_setpointercapture_relatedtarget-manual.html]
   support-files = pointerevent_setpointercapture_relatedtarget-manual.html
   disabled = should be investigated
 [test_pointerevent_setpointercapture_to_same_element_twice-manual.html]

--- a/dom/events/test/pointerevents/mochitest_support_external.js
+++ b/dom/events/test/pointerevents/mochitest_support_external.js
@@ -76,80 +76,91 @@ var MouseEventHelper = (function() {
     },
 
     checkExitState: function() {
       ok(!this.BUTTONS_STATE, "Mismatched mousedown/mouseup caught.");
     }
   };
 }) ();
 
+function createMouseEvent(aEventType, aParams) {
+  var eventObj = {type: aEventType};
+
+  // Default to mouse.
+  eventObj.inputSource =
+    (aParams && "inputSource" in aParams) ? aParams.inputSource :
+                                          MouseEvent.MOZ_SOURCE_MOUSE;
+  // Compute pointerId
+  eventObj.id =
+    (eventObj.inputSource === MouseEvent.MOZ_SOURCE_MOUSE) ? MouseEventHelper.MOUSE_ID :
+                                                             MouseEventHelper.PEN_ID;
+  // Check or generate a |button| value.
+  var isButtonEvent = aEventType === "mouseup" || aEventType === "mousedown";
+
+  // Set |button| to the default value first.
+  eventObj.button = isButtonEvent ? MouseEventHelper.BUTTON_LEFT
+                                  : MouseEventHelper.BUTTON_NONE;
+
+  // |button| is passed, use and check it.
+  if (aParams && "button" in aParams) {
+    var hasButtonValue = (aParams.button !== MouseEventHelper.BUTTON_NONE);
+    ok(!isButtonEvent || hasButtonValue,
+       "Inappropriate |button| value caught.");
+    eventObj.button = aParams.button;
+  }
+
+  // Generate a |buttons| value and update buttons state
+  var buttonsMask = MouseEventHelper.computeButtonsMaskFromButton(eventObj.button);
+  switch(aEventType) {
+    case "mousedown":
+      MouseEventHelper.BUTTONS_STATE |= buttonsMask; // Set button flag.
+      break;
+    case "mouseup":
+      MouseEventHelper.BUTTONS_STATE &= ~buttonsMask; // Clear button flag.
+      break;
+  }
+  eventObj.buttons = MouseEventHelper.BUTTONS_STATE;
+
+  // Replace the button value for mousemove events.
+  // Since in widget level design, even when no button is pressed at all, the
+  // value of WidgetMouseEvent.button is still 0, which is the same value as
+  // the one for mouse left button.
+  if (aEventType === "mousemove") {
+    eventObj.button = MouseEventHelper.BUTTON_LEFT;
+  }
+  return eventObj;
+}
+
 // Helper function to send MouseEvent with different parameters
 function sendMouseEvent(int_win, elemId, mouseEventType, params) {
   var elem = int_win.document.getElementById(elemId);
-  if(!!elem) {
+  if (elem) {
     var rect = elem.getBoundingClientRect();
-    var eventObj = {type: mouseEventType};
-
-    // Default to mouse.
-    eventObj.inputSource =
-      (params && "inputSource" in params) ? params.inputSource :
-                                            MouseEvent.MOZ_SOURCE_MOUSE;
-    // Compute pointerId
-    eventObj.id =
-      (eventObj.inputSource === MouseEvent.MOZ_SOURCE_MOUSE) ? MouseEventHelper.MOUSE_ID :
-                                                               MouseEventHelper.PEN_ID;
-    // Check or generate a |button| value.
-    var isButtonEvent = mouseEventType === "mouseup" ||
-                        mouseEventType === "mousedown";
-
-    // Set |button| to the default value first.
-    eventObj.button = isButtonEvent ? MouseEventHelper.BUTTON_LEFT
-                                    : MouseEventHelper.BUTTON_NONE;
-
-    // |button| is passed, use and check it.
-    if (params && "button" in params) {
-      var hasButtonValue = (params.button !== MouseEventHelper.BUTTON_NONE);
-      ok(!isButtonEvent || hasButtonValue,
-         "Inappropriate |button| value caught.");
-      eventObj.button = params.button;
-    }
-
-    // Generate a |buttons| value and update buttons state
-    var buttonsMask = MouseEventHelper.computeButtonsMaskFromButton(eventObj.button);
-    switch(mouseEventType) {
-      case "mousedown":
-        MouseEventHelper.BUTTONS_STATE |= buttonsMask; // Set button flag.
-        break;
-      case "mouseup":
-        MouseEventHelper.BUTTONS_STATE &= ~buttonsMask; // Clear button flag.
-        break;
-    }
-    eventObj.buttons = MouseEventHelper.BUTTONS_STATE;
-
-    // Replace the button value for mousemove events.
-    // Since in widget level design, even when no button is pressed at all, the
-    // value of WidgetMouseEvent.button is still 0, which is the same value as
-    // the one for mouse left button.
-    if (mouseEventType === "mousemove") {
-      eventObj.button = MouseEventHelper.BUTTON_LEFT;
-    }
+    var eventObj = createMouseEvent(mouseEventType, params);
 
     // Default to the center of the target element but we can still send to a
     // position outside of the target element.
     var offsetX = params && "offsetX" in params ? params.offsetX : rect.width / 2;
     var offsetY = params && "offsetY" in params ? params.offsetY : rect.height / 2;
 
     console.log(elemId, eventObj);
     synthesizeMouse(elem, offsetX, offsetY, eventObj, int_win);
 
   } else {
     is(!!elem, true, "Document should have element with id: " + elemId);
   }
 }
 
+// Helper function to send MouseEvent with position
+function sendMouseEventAtPoint(aWindow, aLeft, aTop, aMouseEventType, aParams) {
+  var eventObj = createMouseEvent(aMouseEventType, aParams);
+  console.log(eventObj);
+  synthesizeMouseAtPoint(aLeft, aTop, eventObj, aWindow);
+}
+
 // Touch Event Helper Object
 var TouchEventHelper = {
   // State
   TOUCH_ID: utils.DEFAULT_TOUCH_POINTER_ID,
   TOUCH_STATE: false,
 
   // Utils
   checkExitState: function() {

--- a/dom/events/test/pointerevents/test_pointerevent_setpointercapture_inactive_button_mouse-manual.html
+++ b/dom/events/test/pointerevents/test_pointerevent_setpointercapture_inactive_button_mouse-manual.html
@@ -12,17 +12,18 @@ https://bugzilla.mozilla.org/show_bug.cg
     <script type="text/javascript" src="mochitest_support_external.js"></script>
     <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
     <script type="text/javascript">
       SimpleTest.waitForExplicitFinish();
       function startTest() {
         runTestInNewWindow("pointerevent_setpointercapture_inactive_button_mouse-manual.html");
       }
       function executeTest(int_win) {
-        sendMouseEvent(int_win, "target1", "mousemove");
-        sendMouseEvent(int_win, "target0", "mousemove");
-        sendMouseEvent(int_win, "target1", "mousemove");
+        let target0 = int_win.document.getElementById("target0");
+        let rect = target0.getBoundingClientRect();
+        sendMouseEventAtPoint(int_win, rect.left + 1, rect.top + 1, "mousemove");
+        sendMouseEventAtPoint(int_win, rect.left - 1, rect.top - 1, "mousemove");
       }
     </script>
   </head>
   <body>
   </body>
 </html>