As I'm working on bug 1697575 which will move the account creation into a Tab, I stumbled upon an issue where the focus is stolen by the Privacy policy tab we open on first run.

Since we're opening that tab with the background: true attribute to let it open "behind" the currently opened tab, the focus should remain on the current tab.
Currently it's stolen by the tabmail element.
https://searchfox.org/comm-central/rev/9162fde155e18e51ff6668916ecf4f0ce188315a/mail/base/content/specialTabs.js#1097-1100

Issues:

• The focus/cursor moves away while typing in the account config form.
• If the auto config completes the account creation process and closes the current tab to move back to the primary Mail Tab in the exact moment when the Privacy policy Tab is opened, the focus gets stolen and the UI doesn't properly load in the Mail tab.

Similar to bug 1695155 but not directly related.
This problem can also be potentially detrimental for keyboard users as the focus is suddenly stolen by a background tab.

Pushed by mkmelin@iki.fi:
https://hg.mozilla.org/comm-central/rev/cd05826afab9
Prevent blurring the current element and focusing on a new Tab if it was opened in the background. r=darktrojan