diff --git a/modules/libpr0n/public/imgIContainer.idl b/modules/libpr0n/public/imgIContainer.idl
index 10533a44136d..470c8ea8175f 100644
--- a/modules/libpr0n/public/imgIContainer.idl
+++ b/modules/libpr0n/public/imgIContainer.idl
@@ -52,7 +52,20 @@ interface imgIDecoderObserver;
 #include "gfxPattern.h"
 #include "gfxASurface.h"
 #include "nsRect.h"
+#include "limits.h"
+
 class nsIFrame;
+
+namespace mozilla  {
+namespace imagelib {
+  /**
+   * A sentinel value that can be passed to various imagelib methods
+   * to represent "the full image space".
+   */
+  static const nsIntRect kFullImageSpaceRect(0, 0, INT_MAX, INT_MAX);
+}
+}
+
 %}
 
 [ptr] native gfxImageSurface(gfxImageSurface);