First part of fix for bug 309721, r+sr=jst

dom/public/base/nsPIDOMWindow.h

@@ -71,8 +71,8 @@ class nsPresContext;
 struct nsTimeout;
 
 #define NS_PIDOMWINDOW_IID \
-{ 0xca692511, 0x8558, 0x4307, \
-  { 0x84, 0xdb, 0x77, 0x28, 0xec, 0xed, 0xb1, 0xd2 } }
+{ 0xad6640fb, 0x575e, 0x4bfe, \
+ { 0x92, 0x92, 0xe6, 0x36, 0xfb, 0xee, 0xff, 0x3d } }
 
 class nsPIDOMWindow : public nsIDOMWindowInternal
 {
@@ -384,6 +384,7 @@ public:
   virtual void SetOpenerWindow(nsIDOMWindowInternal *aOpener,
                                PRBool aOriginalOpener) = 0;
 
+  virtual void EnsureSizeUpToDate() = 0;
 
 protected:
   // The nsPIDOMWindow constructor. The aOuterWindow argument should

dom/src/base/nsGlobalWindow.h

@@ -240,6 +240,7 @@ public:
                                   PRBool aClearScopeHint);
   virtual NS_HIDDEN_(void) SetOpenerWindow(nsIDOMWindowInternal *aOpener,
                                            PRBool aOriginalOpener);
+  virtual NS_HIDDEN_(void) EnsureSizeUpToDate();
 
   // nsIDOMViewCSS
   NS_DECL_NSIDOMVIEWCSS
@@ -402,7 +403,6 @@ protected:
                            const nsAString &aPopupWindowFeatures);
 
   void FlushPendingNotifications(mozFlushType aType);
-  void EnsureSizeUpToDate();
   void EnsureReflowFlushAndPaint();
   nsresult CheckSecurityWidthAndHeight(PRInt32* width, PRInt32* height);
   nsresult CheckSecurityLeftAndTop(PRInt32* left, PRInt32* top);

dom/src/base/nsScreen.cpp

@@ -38,7 +38,7 @@
 
 #include "nscore.h"
 #include "nsScreen.h"
-#include "nsIDOMWindow.h"
+#include "nsPIDOMWindow.h"
 #include "nsIScriptGlobalObject.h"
 #include "nsIDocShell.h"
 #include "nsIDeviceContext.h"
@@ -46,7 +46,7 @@
 #include "nsCOMPtr.h"
 #include "nsIDocumentViewer.h"
 #include "nsDOMClassInfo.h"
-
+#include "nsIInterfaceRequestorUtils.h"
 
 //
 //  Screen class implementation
@@ -201,6 +201,18 @@ nsScreen::GetDeviceContext()
   if(!mDocShell)
     return nsnull;
 
+  // Now make sure our size is up to date.  That will mean that the device
+  // context does the right thing on multi-monitor systems when we return it to
+  // the caller.  It will also make sure that our prescontext has been created,
+  // if we're supposed to have one.
+  nsCOMPtr<nsPIDOMWindow> win = do_GetInterface(mDocShell);
+  if (!win) {
+    // No reason to go on
+    return nsnull;
+  }
+
+  win->EnsureSizeUpToDate();
+  
   nsCOMPtr<nsIContentViewer> contentViewer;
   mDocShell->GetContentViewer(getter_AddRefs(contentViewer));