Accessing sidebar content from main window

[Manoj M]

I am trying to develop an extension, in that I want to change a value in
sidebar content when view changed(using RegisterViewChangeCB) in gmail
interface. How will I access sidebar content from mainwindow? I was able to
access mainwindow from sidebar content using

var mainWindow =
window.QueryInterface(Components.interfaces.nsIInterfaceRequestor)
.getInterface(Components.interfaces.nsIWebNavigation)

.QueryInterface(Components.interfaces.nsIDocShellTreeItem)
.rootTreeItem

.QueryInterface(Components.interfaces.nsIInterfaceRequestor)
.getInterface(Components.interfaces.nsIDOMWindow);

var doc = mainWindow.getBrowser().selectedBrowser.contentWindow.document;

Thanks for any help

Regards,
Manoj

[Dave Townsend]

https://developer.mozilla.org/en/Working_with_windows_in_chrome_code#Accessing_a_document_in_the_sidebar