User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.6) Gecko/20040113 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.6) Gecko/20040113 Currently, it's impossible to use the "persist" attribute on a tabbox to make the selected tab persist. Neither <tabpanels persist="selectedIndex" ...>, nor <tab persist="selected"> does the trick. This may be related to bug#245224 Reproducible: Always Steps to Reproduce: Actual Results: Attribute is correctly saved in the localstore.rdf, but when reopening the window containing the tabbox, the saved value is not used and the selected tab is always the first one (index=0). Expected Results: When reopening the window displaying the tabbox, the selected tab in the tabbox is the tab that was selected the last time. workaround : XUL : <window id="main-window" persist="tabSelectedIndex" onload="onWinLoad(event)" onunload="onWinUnload(event)" ... > JS : function onWinUnload(evt) { document.getElementById('main-window').setAttribute('tabSelectedIndex', document.getElementById('myTabBox').selectedIndex ) ; } function onWinLoad(evt) { document.getElementById('myTabBox').selectedIndex = document.getElementById('main-window').getAttribute('tabSelectedIndex') ; }

Probably bug 245224 and this bug are just symptoms of the same problem. Adding a dependency for now. Confirming with a current Linux build.

(In reply to comment #0) This workaround maybe a little bit easier to use: function persistTabboxSelectedIndexHack(tabboxId) { // hack hack hack // See https://bugzilla.mozilla.org/attachment.cgi?id=192394 const tabbox = document.getElementById(tabboxId); tabbox.setAttribute("selectedIndex", tabbox.selectedIndex); } <tabbox id="test-tabbox" persist="selectedIndex"> <tabs onselect="persistTabboxSelectedIndexHack('test-tabbox')"> ....

Fix by bug 370742