diff --git a/widget/public/nsIBaseWindow.idl b/widget/public/nsIBaseWindow.idl
index 9cec9130fe4..a3b57199982 100644
--- a/widget/public/nsIBaseWindow.idl
+++ b/widget/public/nsIBaseWindow.idl
@@ -185,5 +185,21 @@ interface nsIBaseWindow : nsISupports
 	*/
 	void setFocus();
 
+	/* This is called when focus is available for the taking because of 
+	tabbing through an object.  In any case this is called on an object to 
+	allow it to take focus if it desires.  If the aCurrentFocus object is
+	the object being called, then the object being called should offer focus to
+	it's parent.  If the aCurrentFocus is a child of the object being called,
+	the object being called should set the focus to the next sibling to the
+	aCurrentFocus object.  Otherwise it should take focus for itself.  If the
+	object being called can not take focus for itself it should offer focus to
+	it's parent.  Note an object should not take focus for itself by giving it
+	to a child.  In most cases this function is being called because the child
+	is trying to give up focus. */
+	void focusAvailable(in nsIBaseWindow aCurrentFocus, out boolean aTookFocus);
+
+	/*
+	Title of the window.
+	*/
 	attribute wstring title;
 };