diff --git a/embedding/browser/activex/src/control/WebBrowserContainer.cpp b/embedding/browser/activex/src/control/WebBrowserContainer.cpp
index 7a6df091d75a..c8eaa57e3361 100644
--- a/embedding/browser/activex/src/control/WebBrowserContainer.cpp
+++ b/embedding/browser/activex/src/control/WebBrowserContainer.cpp
@@ -487,6 +487,14 @@ CWebBrowserContainer::ShowModal()
 	return NS_OK;
 }
 
+NS_IMETHODIMP
+CWebBrowserContainer::IsModal(PRBool *_retval)
+{
+	// we're not
+	*_retval = PR_FALSE;
+	return NS_OK;
+}
+
 NS_IMETHODIMP
 CWebBrowserContainer::ExitModalLoop(nsresult aStatus)
 {
@@ -737,6 +745,14 @@ CWebBrowserContainer::ShowAsModal(void)
 	return NS_ERROR_FAILURE;
 }
 
+NS_IMETHODIMP
+CWebBrowserContainer::IsWindowModal(PRBool *_retval)
+{
+	// we're not
+	*_retval = PR_FALSE;
+	return NS_OK;
+}
+
 NS_IMETHODIMP
 CWebBrowserContainer::ExitModalEventLoop(nsresult aStatus)
 {
diff --git a/embedding/browser/gtk/src/GtkMozEmbedChrome.cpp b/embedding/browser/gtk/src/GtkMozEmbedChrome.cpp
index 8995b71ab7a4..8912ebbf9c37 100644
--- a/embedding/browser/gtk/src/GtkMozEmbedChrome.cpp
+++ b/embedding/browser/gtk/src/GtkMozEmbedChrome.cpp
@@ -435,6 +435,13 @@ NS_IMETHODIMP GtkMozEmbedChrome::ShowAsModal(void)
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
+NS_IMETHODIMP GtkMozEmbedChrome::IsWindowModal(PRBool *_retval)
+{
+  PR_LOG(mozEmbedLm, PR_LOG_DEBUG, ("GtkMozEmbedChrome::IsWindowModal\n"));
+  *_retval = PR_FALSE;
+  return NS_OK;
+}
+
 NS_IMETHODIMP GtkMozEmbedChrome::ExitModalEventLoop(nsresult aStatus)
 {
   PR_LOG(mozEmbedLm, PR_LOG_DEBUG, ("GtkMozEmbedChrome::ExitModalLoop\n"));
@@ -605,6 +612,13 @@ NS_IMETHODIMP GtkMozEmbedChrome::ShowModal(void)
   return NS_OK;
 }
 
+NS_IMETHODIMP GtkMozEmbedChrome::IsModal(PRBool *_retval)
+{
+  PR_LOG(mozEmbedLm, PR_LOG_DEBUG, ("GtkMozEmbedChrome::IsModal\n"));
+  *_retval = PR_FALSE;
+  return NS_OK;
+}
+
 NS_IMETHODIMP GtkMozEmbedChrome::ExitModalLoop(nsresult aStatus)
 {
   PR_LOG(mozEmbedLm, PR_LOG_DEBUG, ("GtkMozEmbedChrome::ExitModalLoop\n"));
diff --git a/embedding/browser/photon/src/PhMozEmbedChrome.cpp b/embedding/browser/photon/src/PhMozEmbedChrome.cpp
index 8bb5693fcd0c..8c7eef6482f0 100644
--- a/embedding/browser/photon/src/PhMozEmbedChrome.cpp
+++ b/embedding/browser/photon/src/PhMozEmbedChrome.cpp
@@ -436,6 +436,13 @@ NS_IMETHODIMP PhMozEmbedChrome::ShowAsModal(void)
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
+NS_IMETHODIMP PhMozEmbedChrome::IsWindowModal(PRBool *_retval)
+{
+  PR_LOG(mozEmbedLm, PR_LOG_DEBUG, ("PhMozEmbedChrome::IsWindowModal\n"));
+  *_retval = PR_FALSE;
+  return NS_OK;
+}
+
 NS_IMETHODIMP PhMozEmbedChrome::ExitModalEventLoop(nsresult aStatus)
 {
   PR_LOG(mozEmbedLm, PR_LOG_DEBUG, ("PhMozEmbedChrome::ExitModalLoop\n"));
@@ -605,6 +612,13 @@ NS_IMETHODIMP PhMozEmbedChrome::ShowModal(void)
   return NS_OK;
 }
 
+NS_IMETHODIMP PhMozEmbedChrome::IsModal(PRBool *_retval)
+{
+  PR_LOG(mozEmbedLm, PR_LOG_DEBUG, ("PhMozEmbedChrome::IsModal\n"));
+  *_retval = PR_FALSE;
+  return NS_OK;
+}
+
 NS_IMETHODIMP PhMozEmbedChrome::ExitModalLoop(nsresult aStatus)
 {
   PR_LOG(mozEmbedLm, PR_LOG_DEBUG, ("PhMozEmbedChrome::ExitModalLoop\n"));
diff --git a/embedding/tests/gtkEmbed/WebBrowserChrome.cpp b/embedding/tests/gtkEmbed/WebBrowserChrome.cpp
index 7cc7d55ed024..ee2cce62946e 100644
--- a/embedding/tests/gtkEmbed/WebBrowserChrome.cpp
+++ b/embedding/tests/gtkEmbed/WebBrowserChrome.cpp
@@ -179,6 +179,12 @@ NS_IMETHODIMP WebBrowserChrome::ShowAsModal(void)
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
+NS_IMETHODIMP WebBrowserChrome::IsWindowModal(PRBool *_retval)
+{
+  *_retval = PR_FALSE;
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
 NS_IMETHODIMP WebBrowserChrome::ExitModalEventLoop(nsresult aStatus)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
diff --git a/embedding/tests/winEmbed/WebBrowserChrome.cpp b/embedding/tests/winEmbed/WebBrowserChrome.cpp
index 2dc4b0518eff..25da22ac109d 100644
--- a/embedding/tests/winEmbed/WebBrowserChrome.cpp
+++ b/embedding/tests/winEmbed/WebBrowserChrome.cpp
@@ -174,6 +174,12 @@ NS_IMETHODIMP WebBrowserChrome::ShowAsModal(void)
   return NS_ERROR_NOT_IMPLEMENTED;
 }
 
+NS_IMETHODIMP WebBrowserChrome::IsWindowModal(PRBool *_retval)
+{
+  *_retval = PR_FALSE;
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
 NS_IMETHODIMP WebBrowserChrome::ExitModalEventLoop(nsresult aStatus)
 {
   return NS_ERROR_NOT_IMPLEMENTED;
diff --git a/webshell/tests/viewer/nsWebBrowserChrome.cpp b/webshell/tests/viewer/nsWebBrowserChrome.cpp
index ff3736cc11c5..62d2fda54327 100644
--- a/webshell/tests/viewer/nsWebBrowserChrome.cpp
+++ b/webshell/tests/viewer/nsWebBrowserChrome.cpp
@@ -182,6 +182,12 @@ NS_IMETHODIMP nsWebBrowserChrome::ShowAsModal()
    return NS_ERROR_FAILURE;
 }
 
+NS_IMETHODIMP nsWebBrowserChrome::IsWindowModal(PRBool *_retval)
+{
+   NS_ERROR("Haven't Implemented this yet");
+   return NS_ERROR_FAILURE;
+}
+
 NS_IMETHODIMP nsWebBrowserChrome::ExitModalEventLoop(nsresult aStatus)
 {
    NS_ERROR("Haven't Implemented this yet");