diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
index e5129c42277..3c58a304e47 100644
--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -6539,6 +6539,14 @@ nsDocShell::CreateAboutBlankContentViewer(nsIPrincipal* aPrincipal,
 
         SetCurrentURI(blankDoc->GetDocumentURI(), nsnull, PR_TRUE);
         rv = mIsBeingDestroyed ? NS_ERROR_NOT_AVAILABLE : NS_OK;
+
+        if (NS_SUCCEEDED(rv)) {
+          nsCOMPtr<nsIPresShell> shell = blankDoc->GetShell();
+          if (shell && !shell->DidInitialReflow()) {
+            nsRect r = shell->GetPresContext()->GetVisibleArea();
+            shell->InitialReflow(r.width, r.height);
+          }
+        }
       }
     }
   }
diff --git a/docshell/test/Makefile.in b/docshell/test/Makefile.in
index 887a8a4a887..7cd2ea52fb3 100644
--- a/docshell/test/Makefile.in
+++ b/docshell/test/Makefile.in
@@ -93,8 +93,10 @@ _TEST_FILES = \
 		test_bug590573.html \
 		file_bug590573_1.html \
 		file_bug590573_2.html \
+		test_bug598895.html \
 		test_bug634834.html \
 		file_bug634834.html \
+		test_bug637644.html \
 		$(NULL)
 
 ifeq ($(MOZ_WIDGET_TOOLKIT),cocoa)
diff --git a/docshell/test/test_bug598895.html b/docshell/test/test_bug598895.html
new file mode 100644
index 00000000000..f99c11d4124
--- /dev/null
+++ b/docshell/test/test_bug598895.html
@@ -0,0 +1,54 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=598895
+-->
+<head>
+  <title>Test for Bug 598895</title>
+  <script type="application/javascript" src="/MochiKit/packed.js"></script>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/WindowSnapshot.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=598895">Mozilla Bug 598895</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 598895 **/
+SimpleTest.waitForExplicitFinish();
+
+addLoadEvent(function() {
+var win1 = window.open();
+win1.document.body.textContent = "Should show";
+
+var windowsLoaded = 0;
+
+window.onmessage = function (ev) {
+  is(ev.data, "loaded", "Message should be 'loaded'");
+  if (++windowsLoaded == 2) {
+    var one = snapshotWindow(win1);
+    var two = snapshotWindow(win2);
+    var three = snapshotWindow(win3);
+    win1.close();
+    win2.close();
+    win3.close();
+    ok(compareSnapshots(one, two, true)[0], "Popups should look identical");
+    ok(compareSnapshots(one, three, false)[0], "Popups should not look identical");
+
+    SimpleTest.finish();
+  }
+}
+
+var win2 = window.open("data:text/html,<script>window.onload = function() { opener.postMessage('loaded', '*'); }</" + "script><body>Should show</body>");
+
+var win3 = window.open("data:text/html,<script>window.onload = function() { opener.postMessage('loaded', '*'); }</" + "script><body></body>");
+});
+</script>
+</pre>
+</body>
+</html>
diff --git a/docshell/test/test_bug637644.html b/docshell/test/test_bug637644.html
new file mode 100644
index 00000000000..0f769c77ba2
--- /dev/null
+++ b/docshell/test/test_bug637644.html
@@ -0,0 +1,54 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=637644
+-->
+<head>
+  <title>Test for Bug 637644</title>
+  <script type="application/javascript" src="/MochiKit/packed.js"></script>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/WindowSnapshot.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=637644">Mozilla Bug 637644</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 637644 **/
+SimpleTest.waitForExplicitFinish();
+
+addLoadEvent(function() {
+var win1 = window.open("", "", "height=500,width=500");
+win1.document.body.textContent = "Should show";
+
+var windowsLoaded = 0;
+
+window.onmessage = function (ev) {
+  is(ev.data, "loaded", "Message should be 'loaded'");
+  if (++windowsLoaded == 2) {
+    var one = snapshotWindow(win1);
+    var two = snapshotWindow(win2);
+    var three = snapshotWindow(win3);
+    win1.close();
+    win2.close();
+    win3.close();
+    ok(compareSnapshots(one, two, true)[0], "Popups should look identical");
+    ok(compareSnapshots(one, three, false)[0], "Popups should not look identical");
+
+    SimpleTest.finish();
+  }
+}
+
+var win2 = window.open("data:text/html,<script>window.onload = function() { opener.postMessage('loaded', '*'); }</" + "script><body>Should show</body>", "", "height=500,width=500");
+
+var win3 = window.open("data:text/html,<script>window.onload = function() { opener.postMessage('loaded', '*'); }</" + "script><body></body>", "", "height=500,width=500");
+});
+</script>
+</pre>
+</body>
+</html>
