diff --git a/mozilla/content/base/src/nsGenericElement.cpp b/mozilla/content/base/src/nsGenericElement.cpp
index 9036eedda14..357900afb0c 100644
--- a/mozilla/content/base/src/nsGenericElement.cpp
+++ b/mozilla/content/base/src/nsGenericElement.cpp
@@ -96,6 +96,9 @@
 #include "nsIServiceManager.h"
 #include "nsIDOMEventListener.h"
 
+#include "nsIWebNavigation.h"
+#include "nsIBaseWindow.h"
+
 #include "jsapi.h"
 
 #include "nsIDOMXPathEvaluator.h"
@@ -2422,6 +2425,34 @@ nsGenericElement::SetFocus(nsPresContext* aPresContext)
   }
 }
 
+// static
+PRBool
+nsGenericElement::ShouldFocus(nsIContent *aContent)
+{
+  PRBool visible = PR_TRUE;
+
+  // Figure out if we're focusing an element in an inactive (hidden)
+  // tab (whose docshell is not visible), if so, drop this focus
+  // request on the floor
+
+  nsIDocument *document = aContent->GetDocument();
+
+  if (document) {
+    nsIScriptGlobalObject *sgo = document->GetScriptGlobalObject();
+
+    if (sgo) {
+      nsCOMPtr<nsIWebNavigation> webNav(do_GetInterface(sgo));
+      nsCOMPtr<nsIBaseWindow> baseWin(do_QueryInterface(webNav));
+
+      if (baseWin) {
+        baseWin->GetVisibility(&visible);
+      }
+    }
+  }
+
+  return visible;
+}
+
 nsIContent*
 nsGenericElement::GetBindingParent() const
 {
diff --git a/mozilla/content/base/src/nsGenericElement.h b/mozilla/content/base/src/nsGenericElement.h
index 135b7a86a55..0a47fe343c1 100644
--- a/mozilla/content/base/src/nsGenericElement.h
+++ b/mozilla/content/base/src/nsGenericElement.h
@@ -641,6 +641,8 @@ public:
   static PRBool HasMutationListeners(nsIContent* aContent,
                                      PRUint32 aType);
 
+  static PRBool ShouldFocus(nsIContent *aContent);
+
   static nsresult InitHashes();
 
   static PLDHashTable sEventListenerManagersHash;
diff --git a/mozilla/content/html/content/src/nsHTMLAnchorElement.cpp b/mozilla/content/html/content/src/nsHTMLAnchorElement.cpp
index 99a190a4dcd..d7b24a2f5b8 100644
--- a/mozilla/content/html/content/src/nsHTMLAnchorElement.cpp
+++ b/mozilla/content/html/content/src/nsHTMLAnchorElement.cpp
@@ -200,7 +200,9 @@ nsHTMLAnchorElement::Blur()
 NS_IMETHODIMP
 nsHTMLAnchorElement::Focus()
 {
-  SetElementFocus(PR_TRUE);
+  if (ShouldFocus(this)) {
+    SetElementFocus(PR_TRUE);
+  }
 
   return NS_OK;
 }
diff --git a/mozilla/content/html/content/src/nsHTMLButtonElement.cpp b/mozilla/content/html/content/src/nsHTMLButtonElement.cpp
index a8e7b4ceb71..8e960635cf7 100644
--- a/mozilla/content/html/content/src/nsHTMLButtonElement.cpp
+++ b/mozilla/content/html/content/src/nsHTMLButtonElement.cpp
@@ -184,7 +184,9 @@ nsHTMLButtonElement::Blur()
 NS_IMETHODIMP
 nsHTMLButtonElement::Focus()
 {
-  SetElementFocus(PR_TRUE);
+  if (ShouldFocus(this)) {
+    SetElementFocus(PR_TRUE);
+  }
 
   return NS_OK;
 }
diff --git a/mozilla/content/html/content/src/nsHTMLInputElement.cpp b/mozilla/content/html/content/src/nsHTMLInputElement.cpp
index c3f2def5967..3b702e14a20 100644
--- a/mozilla/content/html/content/src/nsHTMLInputElement.cpp
+++ b/mozilla/content/html/content/src/nsHTMLInputElement.cpp
@@ -1037,7 +1037,9 @@ nsHTMLInputElement::Blur()
 NS_IMETHODIMP
 nsHTMLInputElement::Focus()
 {
-  SetElementFocus(PR_TRUE);
+  if (ShouldFocus(this)) {
+    SetElementFocus(PR_TRUE);
+  }
 
   return NS_OK;
 }
diff --git a/mozilla/content/html/content/src/nsHTMLSelectElement.cpp b/mozilla/content/html/content/src/nsHTMLSelectElement.cpp
index 1af46ad223d..29ec62ddad7 100644
--- a/mozilla/content/html/content/src/nsHTMLSelectElement.cpp
+++ b/mozilla/content/html/content/src/nsHTMLSelectElement.cpp
@@ -1568,7 +1568,9 @@ nsHTMLSelectElement::Blur()
 NS_IMETHODIMP
 nsHTMLSelectElement::Focus()
 {
-  SetElementFocus(PR_TRUE);
+  if (ShouldFocus(this)) {
+    SetElementFocus(PR_TRUE);
+  }
 
   return NS_OK;
 }
diff --git a/mozilla/content/html/content/src/nsHTMLTextAreaElement.cpp b/mozilla/content/html/content/src/nsHTMLTextAreaElement.cpp
index ac635a01380..e5b5298fac0 100644
--- a/mozilla/content/html/content/src/nsHTMLTextAreaElement.cpp
+++ b/mozilla/content/html/content/src/nsHTMLTextAreaElement.cpp
@@ -225,7 +225,9 @@ nsHTMLTextAreaElement::Blur()
 NS_IMETHODIMP
 nsHTMLTextAreaElement::Focus() 
 {
-  SetElementFocus(PR_TRUE);
+  if (ShouldFocus(this)) {
+    SetElementFocus(PR_TRUE);
+  }
 
   return NS_OK;
 }
diff --git a/mozilla/content/xul/content/src/nsXULElement.cpp b/mozilla/content/xul/content/src/nsXULElement.cpp
index add25e84434..be4597f6d1f 100644
--- a/mozilla/content/xul/content/src/nsXULElement.cpp
+++ b/mozilla/content/xul/content/src/nsXULElement.cpp
@@ -3749,6 +3749,10 @@ nsXULElement::IsAncestor(nsIDOMNode* aParentNode, nsIDOMNode* aChildNode)
 NS_IMETHODIMP
 nsXULElement::Focus()
 {
+    if (!nsGenericElement::ShouldFocus(this)) {
+        return NS_OK;
+    }
+
     // What kind of crazy tries to focus an element without a doc?
     if (!mDocument)
         return NS_OK;