STR 1. Open about:preferences > Home 2. Set New tabs to |Blank Page| 3. Click [+] button in tab strip Actual Results: Default page(i.e., top site etc..) is displayed Expected Results: Blank page

Probably just need to call removePreloadedBrowser from somewhere.. for every window. The preferences code is in content, so it would need to message. Could watch for a specific pref change from each browser window? Or I suppose activity stream could watch for pref change and iterate over windows. k88hudson, any suggestions?

I'd probably go with the approach of listening to the pref change in Activity Stream code and iterating over windows, yeah. I remember this causing weird test failures when we tried to do this before, but I'm not sure. Does this happen with enabling an web extension that overrides new tab as well?

(In reply to Kate Hudson :k88hudson from comment #2) > Does this happen with enabling an web extension that overrides new tab as > well? Looks like no. Not sure if there's special code already to update the preloaded browser. Although this gets me thinking maybe we should react to changes from aboutNewTabService instead of activity stream code.

Oh, turns out when an extension overrides, a new tab is used and not the preloaded one

Comment on attachment 8970754 [details] Bug 1454344 - Setting New tabs to |Blank Page| does not become effective until the 2nd new tab. https://reviewboard.mozilla.org/r/239500/#review245434 ::: browser/components/preferences/in-content/tests/browser_newtab_menu.js:13 (Diff revision 2) > + menuItem.dispatchEvent(cmdEvent); > + } > + > + const newtabMenu = doc.getElementById("newTabMode"); > + const menuItems = newtabMenu.querySelectorAll("menuitem"); > + ok(menuItems[0].selected, "The first item, Home (default), is selected."); I don't suppose there's a way to select by id or something? Index seems a bit fragile

Comment on attachment 8970754 [details] Bug 1454344 - Setting New tabs to |Blank Page| does not become effective until the 2nd new tab. https://reviewboard.mozilla.org/r/239500/#review245434 Clever!

Comment on attachment 8970754 [details] Bug 1454344 - Setting New tabs to |Blank Page| does not become effective until the 2nd new tab. https://reviewboard.mozilla.org/r/239500/#review245434 > I don't suppose there's a way to select by id or something? Index seems a bit fragile I switched the list to ```js const menuHome = doc.querySelector(`#newTabMode menuitem[value="0"]`); const menuBlank = doc.querySelector(`#newTabMode menuitem[value="1"]`); ```

Pushed by edilee@gmail.com: https://hg.mozilla.org/integration/autoland/rev/733115bbb9b5 Setting New tabs to |Blank Page| does not become effective until the 2nd new tab. r=k88hudson