diff --git a/extensions/xforms/nsXFormsActionElement.cpp b/extensions/xforms/nsXFormsActionElement.cpp
index 5f21d5f147b..8dce449b48c 100644
--- a/extensions/xforms/nsXFormsActionElement.cpp
+++ b/extensions/xforms/nsXFormsActionElement.cpp
@@ -109,9 +109,8 @@ nsXFormsActionElement::OnDestroyed() {
 NS_IMETHODIMP
 nsXFormsActionElement::HandleEvent(nsIDOMEvent* aEvent)
 {
-  if (!aEvent) 
-    return NS_ERROR_INVALID_ARG;
-  return HandleAction(aEvent, nsnull);
+  return nsXFormsUtils::EventHandlingAllowed(aEvent, mElement) ?
+           HandleAction(aEvent, nsnull) : NS_OK;
 }
 
 PR_STATIC_CALLBACK(PLDHashOperator) DoDeferredActions(nsISupports * aModel, 
diff --git a/extensions/xforms/nsXFormsActionModuleBase.cpp b/extensions/xforms/nsXFormsActionModuleBase.cpp
index 5ba78797993..f9cd8e236f9 100644
--- a/extensions/xforms/nsXFormsActionModuleBase.cpp
+++ b/extensions/xforms/nsXFormsActionModuleBase.cpp
@@ -78,8 +78,7 @@ NS_IMETHODIMP nsXFormsActionModuleBase::OnDestroyed()
 NS_IMETHODIMP
 nsXFormsActionModuleBase::HandleEvent(nsIDOMEvent* aEvent)
 {
-  if (!aEvent) 
-    return NS_ERROR_INVALID_ARG;
-  return HandleAction(aEvent, nsnull);
+  return nsXFormsUtils::EventHandlingAllowed(aEvent, mElement) ?
+           HandleAction(aEvent, nsnull) : NS_OK;
 }
 
diff --git a/extensions/xforms/nsXFormsContextContainer.cpp b/extensions/xforms/nsXFormsContextContainer.cpp
index 6e54e92982a..420cb943f9c 100644
--- a/extensions/xforms/nsXFormsContextContainer.cpp
+++ b/extensions/xforms/nsXFormsContextContainer.cpp
@@ -174,6 +174,8 @@ nsXFormsContextContainer::HandleDefault(nsIDOMEvent *aEvent,
   if (!type.EqualsLiteral("focus"))
     return nsXFormsControlStub::HandleDefault(aEvent, aHandled);
 
+  if (!nsXFormsUtils::EventHandlingAllowed(aEvent, mElement))
+    return NS_OK;
   /*
    * Either we, or an element we contain, has gotten focus, so we need to set
    * the repeat index. This is done through the \<repeat\> the
diff --git a/extensions/xforms/nsXFormsControlStub.cpp b/extensions/xforms/nsXFormsControlStub.cpp
index 10a4a84a4fa..c21154a5aba 100644
--- a/extensions/xforms/nsXFormsControlStub.cpp
+++ b/extensions/xforms/nsXFormsControlStub.cpp
@@ -66,15 +66,16 @@ nsXFormsHintHelpListener::HandleEvent(nsIDOMEvent* aEvent)
   nsCOMPtr<nsIDOMEventTarget> target;
   aEvent->GetCurrentTarget(getter_AddRefs(target));
   nsCOMPtr<nsIDOMNode> targetNode(do_QueryInterface(target));
-
-  nsCOMPtr<nsIDOMKeyEvent> keyEvent(do_QueryInterface(aEvent));
-  if (keyEvent) {
-    PRUint32 code = 0;
-    keyEvent->GetKeyCode(&code);
-    if (code == nsIDOMKeyEvent::DOM_VK_F1)
-      nsXFormsUtils::DispatchEvent(targetNode, eEvent_Help);
-  } else {
-    nsXFormsUtils::DispatchEvent(targetNode, eEvent_Hint);
+  if (nsXFormsUtils::EventHandlingAllowed(aEvent, targetNode)) {
+    nsCOMPtr<nsIDOMKeyEvent> keyEvent(do_QueryInterface(aEvent));
+    if (keyEvent) {
+      PRUint32 code = 0;
+      keyEvent->GetKeyCode(&code);
+      if (code == nsIDOMKeyEvent::DOM_VK_F1)
+        nsXFormsUtils::DispatchEvent(targetNode, eEvent_Help);
+    } else {
+      nsXFormsUtils::DispatchEvent(targetNode, eEvent_Hint);
+    }
   }
 
   return NS_OK;
@@ -284,7 +285,8 @@ nsXFormsControlStub::HandleDefault(nsIDOMEvent *aEvent,
 {
   NS_ENSURE_ARG(aHandled);
 
-  if (aEvent) {
+  if (nsXFormsUtils::EventHandlingAllowed(aEvent, mElement)) {
+
     // Check that we are the target of the event
     nsCOMPtr<nsIDOMEventTarget> target;
     aEvent->GetTarget(getter_AddRefs(target));
diff --git a/extensions/xforms/nsXFormsDispatchElement.cpp b/extensions/xforms/nsXFormsDispatchElement.cpp
index 4be44f0598c..97265631c3b 100644
--- a/extensions/xforms/nsXFormsDispatchElement.cpp
+++ b/extensions/xforms/nsXFormsDispatchElement.cpp
@@ -108,11 +108,9 @@ nsXFormsDispatchElement::HandleAction(nsIDOMEvent* aEvent,
   docEvent->CreateEvent(NS_LITERAL_STRING("Events"), getter_AddRefs(event));
   event->InitEvent(name, bubbles, cancelable);
 
-  // XXX: What about uiEvent->SetTrusted(?), should these events be
-  // trusted or not?
-
   nsCOMPtr<nsIDOMEventTarget> targetEl = do_QueryInterface(el);
   if (targetEl) {
+    nsXFormsUtils::SetEventTrusted(event, el);
     PRBool defaultActionEnabled;
     targetEl->DispatchEvent(event, &defaultActionEnabled);
   }
diff --git a/extensions/xforms/nsXFormsInputElement.cpp b/extensions/xforms/nsXFormsInputElement.cpp
index c00b29f4235..d16b63c2502 100644
--- a/extensions/xforms/nsXFormsInputElement.cpp
+++ b/extensions/xforms/nsXFormsInputElement.cpp
@@ -259,7 +259,10 @@ nsXFormsInputElement::HandleDefault(nsIDOMEvent *aEvent,
   if (*aHandled || !mIncremental) {
     return NS_OK;
   }
-  
+
+  if (!nsXFormsUtils::EventHandlingAllowed(aEvent, mElement))
+    return NS_OK;
+
   nsAutoString type;
   aEvent->GetType(type);
 
@@ -290,7 +293,8 @@ nsXFormsInputElement::Focus(nsIDOMEvent *aEvent)
 NS_IMETHODIMP
 nsXFormsInputElement::Blur(nsIDOMEvent *aEvent)
 {
-  return UpdateInstanceData();
+  return nsXFormsUtils::EventHandlingAllowed(aEvent, mElement) ?
+           UpdateInstanceData() : NS_OK;
 }
 
 nsresult
diff --git a/extensions/xforms/nsXFormsMessageElement.cpp b/extensions/xforms/nsXFormsMessageElement.cpp
index f139dd3190f..4f2449cbbf6 100644
--- a/extensions/xforms/nsXFormsMessageElement.cpp
+++ b/extensions/xforms/nsXFormsMessageElement.cpp
@@ -270,9 +270,8 @@ nsXFormsMessageElement::OnDestroyed()
 NS_IMETHODIMP
 nsXFormsMessageElement::HandleEvent(nsIDOMEvent* aEvent)
 {
-  if (!aEvent) 
-    return NS_ERROR_INVALID_ARG;
-  return HandleAction(aEvent, nsnull);
+  return nsXFormsUtils::EventHandlingAllowed(aEvent, mElement) ?
+           HandleAction(aEvent, nsnull) : NS_OK;
 }
 
 void
diff --git a/extensions/xforms/nsXFormsModelElement.cpp b/extensions/xforms/nsXFormsModelElement.cpp
index 36586d13625..b98bd47335c 100644
--- a/extensions/xforms/nsXFormsModelElement.cpp
+++ b/extensions/xforms/nsXFormsModelElement.cpp
@@ -358,6 +358,9 @@ nsXFormsModelElement::DoneAddingChildren()
 NS_IMETHODIMP
 nsXFormsModelElement::HandleDefault(nsIDOMEvent *aEvent, PRBool *aHandled)
 {
+  if (!nsXFormsUtils::EventHandlingAllowed(aEvent, mElement))
+    return NS_OK;
+
   *aHandled = PR_TRUE;
 
   nsAutoString type;
@@ -734,6 +737,9 @@ nsXFormsModelElement::OnError(nsresult aStatus,
 NS_IMETHODIMP
 nsXFormsModelElement::HandleEvent(nsIDOMEvent* aEvent)
 {
+  if (!nsXFormsUtils::EventHandlingAllowed(aEvent, mElement))
+    return NS_OK;
+
   nsAutoString type;
   aEvent->GetType(type);
   if (!type.EqualsLiteral("DOMContentLoaded"))
diff --git a/extensions/xforms/nsXFormsSelectElement.cpp b/extensions/xforms/nsXFormsSelectElement.cpp
index 25ca04f170c..db330519f5d 100644
--- a/extensions/xforms/nsXFormsSelectElement.cpp
+++ b/extensions/xforms/nsXFormsSelectElement.cpp
@@ -349,6 +349,9 @@ nsXFormsSelectElement::TryFocus(PRBool* aOK)
 NS_IMETHODIMP
 nsXFormsSelectElement::HandleEvent(nsIDOMEvent *aEvent)
 {
+  if (!nsXFormsUtils::EventHandlingAllowed(aEvent, mElement))
+    return NS_OK;
+
   nsAutoString type;
   aEvent->GetType(type);
 
diff --git a/extensions/xforms/nsXFormsSubmissionElement.cpp b/extensions/xforms/nsXFormsSubmissionElement.cpp
index ef1a81679a1..bedd29ebff9 100644
--- a/extensions/xforms/nsXFormsSubmissionElement.cpp
+++ b/extensions/xforms/nsXFormsSubmissionElement.cpp
@@ -283,6 +283,9 @@ nsXFormsSubmissionElement::OnDestroyed()
 NS_IMETHODIMP
 nsXFormsSubmissionElement::HandleDefault(nsIDOMEvent *aEvent, PRBool *aHandled)
 {
+  if (!nsXFormsUtils::EventHandlingAllowed(aEvent, mElement))
+    return NS_OK;
+
   nsAutoString type;
   aEvent->GetType(type);
   if (type.EqualsLiteral("xforms-submit")) {
diff --git a/extensions/xforms/nsXFormsTriggerElement.cpp b/extensions/xforms/nsXFormsTriggerElement.cpp
index c43022969fa..112b3b4fa01 100644
--- a/extensions/xforms/nsXFormsTriggerElement.cpp
+++ b/extensions/xforms/nsXFormsTriggerElement.cpp
@@ -242,6 +242,9 @@ nsXFormsTriggerElement::HandleDefault(nsIDOMEvent *aEvent, PRBool *aHandled)
     return NS_OK;
   }
 
+  if (!nsXFormsUtils::EventHandlingAllowed(aEvent, mElement))
+    return NS_OK;
+
   nsAutoString type;
   aEvent->GetType(type);
 
@@ -276,8 +279,7 @@ nsXFormsTriggerElement::HandleDefault(nsIDOMEvent *aEvent, PRBool *aHandled)
                        aView,
                        1); // Simple click
 
-  // XXX: What about uiEvent->SetTrusted(?), should these events be
-  // trusted or not?
+  nsXFormsUtils::SetEventTrusted(uiEvent, mElement);
 
   PRBool cancelled;
   return target->DispatchEvent(uiEvent, &cancelled);
@@ -328,6 +330,9 @@ nsXFormsSubmitElement::HandleDefault(nsIDOMEvent *aEvent, PRBool *aHandled)
     return NS_OK;
   }
 
+  if (!nsXFormsUtils::EventHandlingAllowed(aEvent, mElement))
+    return NS_OK;
+
   nsAutoString type;
   aEvent->GetType(type);
   if (!(*aHandled = type.EqualsLiteral("DOMActivate")))
diff --git a/extensions/xforms/nsXFormsUploadElement.cpp b/extensions/xforms/nsXFormsUploadElement.cpp
index 7282db6a354..482be16e752 100644
--- a/extensions/xforms/nsXFormsUploadElement.cpp
+++ b/extensions/xforms/nsXFormsUploadElement.cpp
@@ -211,7 +211,8 @@ nsXFormsUploadElement::Focus(nsIDOMEvent *aEvent)
 NS_IMETHODIMP
 nsXFormsUploadElement::Blur(nsIDOMEvent *aEvent)
 {
-  if (!mInput || !mBoundNode || !mModel)
+  if (!mInput || !mBoundNode || !mModel ||
+      !nsXFormsUtils::EventHandlingAllowed(aEvent, mElement))
     return NS_OK;
 
   nsAutoString value;
diff --git a/extensions/xforms/nsXFormsUtils.cpp b/extensions/xforms/nsXFormsUtils.cpp
index bc87ccd8d78..2714e2b6e55 100644
--- a/extensions/xforms/nsXFormsUtils.cpp
+++ b/extensions/xforms/nsXFormsUtils.cpp
@@ -80,6 +80,9 @@
 #include "nsIDOM3Node.h"
 #include "nsIConsoleService.h"
 #include "nsIStringBundle.h"
+#include "nsIDOMNSEvent.h"
+#include "nsIURI.h"
+#include "nsIPrivateDOMEvent.h"
 
 #define CANCELABLE 0x01
 #define BUBBLES    0x02
@@ -719,17 +722,75 @@ nsXFormsUtils::DispatchEvent(nsIDOMNode* aTarget, nsXFormsEvent aEvent)
   const EventData *data = &sXFormsEventsEntries[aEvent];
   event->InitEvent(NS_ConvertUTF8toUTF16(data->name),
                    data->canBubble, data->canCancel);
-
-  // XXX: What about event->SetTrusted(?) here? Should all these
-  // events be trusted? Right now they're never trusted.
-
+  
   nsCOMPtr<nsIDOMEventTarget> target = do_QueryInterface(aTarget);
   NS_ENSURE_STATE(target);
 
+  SetEventTrusted(event, aTarget);
+
   PRBool defaultActionEnabled;
   return target->DispatchEvent(event, &defaultActionEnabled);
 }
 
+/* static */ nsresult
+nsXFormsUtils::SetEventTrusted(nsIDOMEvent* aEvent, nsIDOMNode* aRelatedNode)
+{
+  nsCOMPtr<nsIDOMNSEvent> event(do_QueryInterface(aEvent));
+  if (event) {
+    PRBool isTrusted = PR_FALSE;
+    event->GetIsTrusted(&isTrusted);
+    if (!isTrusted && aRelatedNode) {
+      nsCOMPtr<nsIDOMDocument> domDoc;
+      aRelatedNode->GetOwnerDocument(getter_AddRefs(domDoc));
+      nsCOMPtr<nsIDocument> doc(do_QueryInterface(domDoc));
+      if (doc) {
+        nsIURI* uri = doc->GetDocumentURI();
+        if (uri) {
+          PRBool isChrome = PR_FALSE;
+          uri->SchemeIs("chrome", &isChrome);
+          if (isChrome) {
+            nsCOMPtr<nsIPrivateDOMEvent> privateEvent(do_QueryInterface(aEvent));
+            NS_ENSURE_STATE(privateEvent);
+            privateEvent->SetTrusted(PR_TRUE);
+          }
+        }
+      }
+    }
+  }
+  return NS_OK;
+}
+
+/* static */ PRBool
+nsXFormsUtils::EventHandlingAllowed(nsIDOMEvent* aEvent, nsIDOMNode* aTarget)
+{
+  PRBool allow = PR_FALSE;
+  if (aEvent && aTarget) {
+    nsCOMPtr<nsIDOMNSEvent> related(do_QueryInterface(aEvent));
+    if (related) {
+      PRBool isTrusted = PR_FALSE;
+      if (NS_SUCCEEDED(related->GetIsTrusted(&isTrusted))) {
+        if (isTrusted) {
+          allow = PR_TRUE;
+        } else {
+          nsCOMPtr<nsIDOMDocument> domDoc;
+          aTarget->GetOwnerDocument(getter_AddRefs(domDoc));
+          nsCOMPtr<nsIDocument> doc(do_QueryInterface(domDoc));
+          if (doc) {
+            nsIURI* uri = doc->GetDocumentURI();
+            if (uri) {
+              PRBool isChrome = PR_FALSE;
+              uri->SchemeIs("chrome", &isChrome);
+              allow = !isChrome;
+            }
+          }
+        }
+      }
+    }
+  }
+  NS_WARN_IF_FALSE(allow, "Event handling not allowed!");
+  return allow;
+}
+
 /* static */ PRBool
 nsXFormsUtils::IsXFormsEvent(const nsAString& aEvent,
                              PRBool& aCancelable,
diff --git a/extensions/xforms/nsXFormsUtils.h b/extensions/xforms/nsXFormsUtils.h
index d0ec9275848..e7cd6349230 100644
--- a/extensions/xforms/nsXFormsUtils.h
+++ b/extensions/xforms/nsXFormsUtils.h
@@ -54,6 +54,7 @@ class nsIXFormsModelElement;
 class nsIURI;
 class nsString;
 class nsIMutableArray;
+class nsIDOMEvent;
 
 #define NS_NAMESPACE_XFORMS              "http://www.w3.org/2002/xforms"
 #define NS_NAMESPACE_XHTML               "http://www.w3.org/1999/xhtml"
@@ -257,7 +258,27 @@ public:
    */
   static NS_HIDDEN_(nsresult)
     DispatchEvent(nsIDOMNode* aTarget, nsXFormsEvent aEvent);
-  
+
+  /**
+   * Sets aEvent trusted if aRelatedNode is in chrome.
+   * When dispatching events in chrome, they should be set trusted
+   * because by default event listeners in chrome handle only trusted
+   * events.
+   * Should be called before any event dispatching in XForms.
+   */
+  static NS_HIDDEN_(nsresult)
+    SetEventTrusted(nsIDOMEvent* aEvent, nsIDOMNode* aRelatedNode);
+
+  /**
+   * Returns PR_TRUE unless aTarget is in chrome and aEvent is not trusted.
+   * This should be used always before handling events. Otherwise if XForms
+   * is used in chrome, it may try to handle events that can be synthesized 
+   * by untrusted content. I.e. content documents may create events using
+   * document.createEvent() and then fire them using target.dispatchEvent();
+   */
+  static NS_HIDDEN_(PRBool)
+    EventHandlingAllowed(nsIDOMEvent* aEvent, nsIDOMNode* aTarget);
+
   /**
    * Returns PR_TRUE, if aEvent is an XForms event, and sets the values
    * of aCancelable and aBubbles parameters according to the event type.