The short version?
this code (copy the whole thing) and hit Evaluate: Components.classes[‘@mozilla.org/appshell/window-mediator;1’].getService(Components.interfaces.nsIWindowMediator).getMostRecentWindow(“mail:3pane”).document.getElementById(“tabmail”).openTab(“contentTab”, {contentPage: “https://wave.google.com/wave/?nouacheck”}); If you’re a Google Voice user, you can pull off a similar persistent Voice inbox tab, per commenter steelpitt’s advice: Components.classes[‘@mozilla.org/appshell/window-mediator;1’].getService(Components.interfaces.nsIWindowMediator).getMostRecentWindow(“mail:3pane”).document.getElementById(“tabmail”).openTab(“contentTab”, {contentPage: “https://google.com/voice/?”}); And, as trstn points out, you can easily enter most any web site as the address in the contentPage section. Heck, you can even keep your web-based Gmail open, if you feel like having a fallback if Thunderbird frustrates you. Learn its search and filter powers (and let it index overnight) Thunderbird’s new search