rem: reference = focusedWindow.__proto__.getSelection.call(focusedWindow); 
add: reference = focusedWindow.getSelection(); 
context:     viewPartialSource : function ( context ) {        var focusedWindow = document.commandDispatcher.focusedWindow;        if (focusedWindow == window)          focusedWindow = content;        var docCharset = null;        if (focusedWindow)          docCharset = "charset=" + focusedWindow.document.characterSet;        // "View Selection Source" and others such as "View MathML Source"        // are mutually exclusive, with the precedence given to the selection        // when there is one        var reference = null;        if (context == "selection")          reference = focusedWindow.__proto__.getSelection.call(focusedWindow);        else if (context == "mathml")          reference = this.target;        else          throw "not reached";        var docUrl = null; // unused (and play nice for fragments generated via XSLT too)        window.openDialog("chrome://global/content/viewPartialSource.xul",                          "_blank", "scrollbars,resizable,chrome,dialog=no",                          docUrl, docCharset, reference, context);    },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/928334d5149e0c90e70bbe1c1fa7994456b23921/browser.js/buggy/browser/base/content/browser.js