diff --git a/layout/reftests/mathml/maction-dynamic-3-ref.html b/layout/reftests/mathml/maction-dynamic-3-ref.html
new file mode 100644
index 00000000000..832c8cab6a4
--- /dev/null
+++ b/layout/reftests/mathml/maction-dynamic-3-ref.html
@@ -0,0 +1,35 @@
+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+<title>dynamic maction 3</title>
+</head>
+
+<body>
+
+<!-- This element generates an invalid markup error. -->
+<!-- We are assuming here that all invalid MathML markups look the same. -->
+<p><math><msup><mi>x</mi></msup></math></p>
+
+<p><math><mtext>__1__</mtext></math></p>
+
+<p><math><mtext>__1__</mtext></math></p>
+
+<p><math><msup><mi>x</mi></msup></math></p>
+
+<p><math><msup><mi>x</mi></msup></math></p>
+
+<p><math><mtext>__1__</mtext></math></p>
+
+<p><math><mtext>__1__</mtext></math></p>
+
+<p><math><mtext>__1__</mtext></math></p>
+
+<p><math><mtext>__1__</mtext></math></p>
+
+<p><math><mtext>__1__</mtext></math></p>
+
+<p><math><mtext>__1__</mtext></math></p>
+
+<p><math><msup><mi>x</mi></msup></math></p>
+
+</body>
+</html>
diff --git a/layout/reftests/mathml/maction-dynamic-3.html b/layout/reftests/mathml/maction-dynamic-3.html
new file mode 100644
index 00000000000..c6dea05f60c
--- /dev/null
+++ b/layout/reftests/mathml/maction-dynamic-3.html
@@ -0,0 +1,137 @@
+<html xmlns="http://www.w3.org/1999/xhtml" class="reftest-wait">
+<head>
+<title>dynamic maction 3</title>
+</head>
+
+<body>
+
+<p>
+<math>
+  <maction id="m1" actiontype="toggle">
+    <mtext>__1__</mtext>
+    <mtext>__2__</mtext>
+  </maction>
+</math>
+</p>
+
+<p>
+<math>
+  <maction id="m2" actiontype="toggle" selection="5">
+    <mtext>__1__</mtext>
+    <mtext>__2__</mtext>
+  </maction>
+</math>
+</p>
+
+<p>
+<math>
+  <maction id="m3" actiontype="toggle" selection="5">
+    <mtext>__1__</mtext>
+    <mtext>__2__</mtext>
+  </maction>
+</math>
+</p>
+
+<p>
+<math>
+  <maction id="m4" actiontype="toggle">
+    <mtext>__1__</mtext>
+    <mtext>__2__</mtext>
+  </maction>
+</math>
+</p>
+
+<p>
+<math>
+  <maction id="m5" actiontype="toggle" selection="5">
+    <mtext>__1__</mtext>
+    <mtext>__2__</mtext>
+  </maction>
+</math>
+</p>
+
+<p>
+<math>
+  <maction id="m6" actiontype="toggle">
+    <mtext>__1__</mtext>
+    <mtext>__2__</mtext>
+  </maction>
+</math>
+</p>
+
+<p>
+<math>
+  <maction id="m7">
+    <mtext>__1__</mtext>
+    <mtext>__2__</mtext>
+  </maction>
+</math>
+</p>
+
+<p>
+<math>
+  <maction id="m8" actiontype="unknown_action_type">
+    <mtext>__1__</mtext>
+    <mtext>__2__</mtext>
+  </maction>
+</math>
+</p>
+
+<p>
+<math>
+  <maction id="m9" selection="5">
+    <mtext>__1__</mtext>
+    <mtext>__2__</mtext>
+  </maction>
+</math>
+</p>
+
+<p>
+<math>
+  <maction id="m10" actiontype="unknown_action_type" selection="5">
+    <mtext>__1__</mtext>
+    <mtext>__2__</mtext>
+  </maction>
+</math>
+</p>
+
+<p>
+<math>
+  <maction id="m11" actiontype="statusline">
+    <mtext>__1__</mtext>
+    <mtext>__2__</mtext>
+  </maction>
+</math>
+</p>
+
+<p>
+<math>
+  <maction id="m12" actiontype="statusline" selection="5">
+    <mtext>__1__</mtext>
+    <mtext>__2__</mtext>
+  </maction>
+</math>
+</p>
+
+<script>
+  function doTest() {
+    document.getElementById("m1").setAttribute("selection", "5");
+    document.getElementById("m2").setAttribute("selection", "1");
+    document.getElementById("m3").setAttribute("actiontype", "statusline");
+    document.getElementById("m4").removeAttribute("actiontype");
+    document.getElementById("m5").setAttribute("actiontype", "unknown_action_type");
+    document.getElementById("m6").setAttribute("actiontype", "unknown_action_type");
+    document.getElementById("m7").setAttribute("actiontype", "toggle");
+    document.getElementById("m8").setAttribute("actiontype", "toggle");
+    document.getElementById("m9").setAttribute("actiontype", "statusline");
+    document.getElementById("m10").setAttribute("actiontype", "statusline");
+    document.getElementById("m11").setAttribute("selection", "5");
+    document.getElementById("m12").setAttribute("actiontype", "toggle");
+  
+    document.documentElement.removeAttribute('class');
+  }
+  window.addEventListener("MozReftestInvalidate", doTest, false);
+</script>
+
+</body>
+</html>
diff --git a/layout/reftests/mathml/reftest.list b/layout/reftests/mathml/reftest.list
index 906b16c4a5e..e827001cde4 100644
--- a/layout/reftests/mathml/reftest.list
+++ b/layout/reftests/mathml/reftest.list
@@ -101,3 +101,4 @@ fails == mstyle-5.xhtml mstyle-5-ref.xhtml # See bug 569125#c29
 == maction-dynamic-embellished-op.html maction-dynamic-embellished-op-ref.html
 == maction-dynamic-1.html maction-dynamic-1-ref.html
 == maction-dynamic-2.html maction-dynamic-2-ref.html
+== maction-dynamic-3.html maction-dynamic-3-ref.html
