With bug 704583 we will get the support of running Mozmill tests in different Firefox processes at the same time. There will be no focus issues anymore. Given its importance we should get this patch landed on each branch of Mozmill down to 1.5.x.
Created attachment 588963 [details] [diff] [review] Patch v1 (Mozmill 1.5.x) Fix for Mozmill 1.5.x. It works wonderful.
Created attachment 588967 [details] [diff] [review] Patch v1 (Mozmill 2.0, master) Same patch with updated location for Mozmill 2.0 and Mozbase.
Landed everywhere: mozbase: https://github.com/mozilla/mozbase/commit/cf874c832d8cec59ca948c9d49e258a444719c06 hotfix-2.0: https://github.com/mozautomation/mozmill/commit/f41be6061b037143eca355600ff0e212ac3a4274 hotfix-1.5: https://github.com/mozautomation/mozmill/commit/987ac9339bfa518cb7efe90ade942d054c67a7d1