Index: src/wp-admin/js/editor.js
===================================================================
--- src/wp-admin/js/editor.js	(revision 29585)
+++ src/wp-admin/js/editor.js	(working copy)
@@ -114,6 +114,12 @@
 			DOM.addClass( wrap_id, 'html-active' );
 			setUserSetting( 'editor', 'html' );
 		}
+		// Reset client window if necessary.
+		(function($) {
+			if ( $(document).scrollTop() > $('div#wpwrap').height()) {
+				window.scroll( 0, $('div#wpwrap').height() );
+			}
+		})(jQuery);
 		return false;
 	},