Teaching the menu bar how to highlight the first item when the ALT key

is pressed.

content/shared/public/nsXULAtomList.h

@@ -71,6 +71,7 @@ XUL_ATOM(xpmenubar, "xpmenubar") // An XP menu bar.
 XUL_ATOM(xpmenu, "xpmenu") // Represents an XP menu
 XUL_ATOM(xpmenubutton, "xpmenubutton") // A titled button (with improved behavior) inside an XP menu.
 XUL_ATOM(xpmenuchildren, "xpmenuchildren") // The XP menu's children.
+XUL_ATOM(menuactive, "menuactive") // Whether or not a menu is active (without necessarily being open)
 
 XUL_ATOM(progressmeter, "progressmeter")
 XUL_ATOM(titledbutton, "titledbutton")

layout/xul/base/src/nsMenuBarFrame.cpp

@@ -28,6 +28,7 @@
 #include "nsINameSpaceManager.h"
 #include "nsIDocument.h"
 #include "nsIDOMEventReceiver.h"
+#include "nsXULAtoms.h"
 
 //
 // NS_NewMenuBarFrame
@@ -88,3 +89,45 @@ nsMenuBarFrame::Init(nsIPresContext&  aPresContext,
 
   return rv;
 }
+
+void
+nsMenuBarFrame::ToggleMenuActiveState()
+{
+  if (IsActive()) {
+    // Deactivate the menu bar
+    mIsActive = PR_FALSE;
+    if (mCurrentMenu) {
+      // Deactivate the menu.
+      mCurrentMenu->UnsetAttribute(kNameSpaceID_None, nsXULAtoms::menuactive, PR_TRUE);
+      mCurrentMenu = nsnull;
+    }
+  }
+  else {
+    // Activate the menu bar
+    mIsActive = PR_TRUE;
+
+    // Set the active menu to be the top left item (e.g., the File menu).
+    // We use an attribute called "active" to track the current active menu.
+    nsCOMPtr<nsIContent> firstMenuItem;
+    GetFirstMenuItem(getter_AddRefs(firstMenuItem));
+    if (firstMenuItem) {
+      // Activate the item.
+      firstMenuItem->SetAttribute(kNameSpaceID_None, nsXULAtoms::menuactive, "true", PR_TRUE);
+
+      // Track this item for keyboard navigation.
+      mCurrentMenu = firstMenuItem.get();
+    }
+  }
+}
+
+void 
+nsMenuBarFrame::GetFirstMenuItem(nsIContent** aMenuItem)
+{
+  PRInt32 childCount;
+  *aMenuItem = nsnull;
+  mContent->ChildCount(childCount);
+  if (childCount > 0) {
+    // We have at least one menu item. Good. Fetch it.
+    mContent->ChildAt(0, *aMenuItem);
+  }
+}

layout/xul/base/src/nsMenuBarFrame.h

@@ -26,11 +26,11 @@
 #include "prtypes.h"
 #include "nsIAtom.h"
 #include "nsCOMPtr.h"
-
 #include "nsToolbarFrame.h"
-
 #include "nsMenuBarListener.h"
 
+class nsIContent;
+
 nsresult NS_NewMenuBarFrame(nsIFrame** aResult) ;
 
 class nsMenuBarFrame : public nsToolbarFrame
@@ -46,10 +46,13 @@ public:
 
 // Non-interface helpers
   PRBool IsActive() { return mIsActive; };
+  void ToggleMenuActiveState();
+  void GetFirstMenuItem(nsIContent** aResult);
 
 protected:
-  nsMenuBarListener* mMenuBarListener;
-  PRBool mIsActive;
+  nsMenuBarListener* mMenuBarListener; // The listener that tells us about key and mouse events.
+  PRBool mIsActive; // Whether or not the menu bar is active (a menu item is highlighted or shown).
+  nsIContent* mCurrentMenu; // The current menu that is active.
 }; // class nsMenuBarFrame
 
 #endif

layout/xul/base/src/nsMenuBarListener.cpp

@@ -50,6 +50,7 @@ NS_IMPL_RELEASE(nsMenuBarListener)
 
 ////////////////////////////////////////////////////////////////////////
 nsMenuBarListener::nsMenuBarListener(nsMenuBarFrame* aMenuBar) 
+:mAltKeyDown(PR_FALSE)
 {
   NS_INIT_REFCNT();
   mMenuBarFrame = aMenuBar;
@@ -186,21 +187,47 @@ nsMenuBarListener::MouseOut(nsIDOMEvent* aMouseEvent)
 
 ////////////////////////////////////////////////////////////////////////
 nsresult
-nsMenuBarListener::KeyUp(nsIDOMEvent* aMouseEvent)
-{
+nsMenuBarListener::KeyUp(nsIDOMEvent* aKeyEvent)
+{  
+  // On a press of the ALT key by itself, we toggle the menu's 
+  // active/inactive state.
+  // Get the ascii key code.
+  nsCOMPtr<nsIDOMUIEvent> theEvent = do_QueryInterface(aKeyEvent);
+  PRUint32 theChar;
+	theEvent->GetKeyCode(&theChar);
+  if (theChar == 18 && mAltKeyDown) {
+    // The ALT key was down and is now up.
+    mAltKeyDown = PR_FALSE;
+    mMenuBarFrame->ToggleMenuActiveState();
+  }
   return NS_OK; // means I am NOT consuming event
 }
 
 ////////////////////////////////////////////////////////////////////////
 nsresult
-nsMenuBarListener::KeyDown(nsIDOMEvent* aMouseEvent)
+nsMenuBarListener::KeyDown(nsIDOMEvent* aKeyEvent)
 {
+  nsCOMPtr<nsIDOMUIEvent> theEvent = do_QueryInterface(aKeyEvent);
+  PRUint32 theChar;
+	theEvent->GetKeyCode(&theChar);
+  if (theChar == 18) {
+    // The ALT key just went down. Track this.
+    mAltKeyDown = PR_TRUE;
+  }
+
   return NS_OK; // means I am NOT consuming event
 }
 
 ////////////////////////////////////////////////////////////////////////
 nsresult
-nsMenuBarListener::KeyPress(nsIDOMEvent* aMouseEvent)
+nsMenuBarListener::KeyPress(nsIDOMEvent* aKeyEvent)
 {
+  nsCOMPtr<nsIDOMUIEvent> theEvent = do_QueryInterface(aKeyEvent);
+
+  // On a press of the ALT key by itself, we toggle the menu's 
+  // active/inactive state.
+  // Test Alt attribute
+	PRBool isAlt = PR_FALSE;
+	theEvent->GetAltKey(&isAlt);
   return NS_OK; // means I am NOT consuming event
 }

layout/xul/base/src/nsMenuBarListener.h

@@ -56,7 +56,8 @@ public:
   NS_DECL_ISUPPORTS
 
 protected:
-  nsMenuBarFrame* mMenuBarFrame;
+  nsMenuBarFrame* mMenuBarFrame; // The menu bar object.
+  PRBool mAltKeyDown;            // Whether or not the ALT key is currently down.
 };
 
 

layout/xul/content/src/nsXULAtomList.h

@@ -71,6 +71,7 @@ XUL_ATOM(xpmenubar, "xpmenubar") // An XP menu bar.
 XUL_ATOM(xpmenu, "xpmenu") // Represents an XP menu
 XUL_ATOM(xpmenubutton, "xpmenubutton") // A titled button (with improved behavior) inside an XP menu.
 XUL_ATOM(xpmenuchildren, "xpmenuchildren") // The XP menu's children.
+XUL_ATOM(menuactive, "menuactive") // Whether or not a menu is active (without necessarily being open)
 
 XUL_ATOM(progressmeter, "progressmeter")
 XUL_ATOM(titledbutton, "titledbutton")