Thunderbird Unresponsive script

This is not a howto fix but a gripe.    When moving large amounts of emails within Thunderbird, you'll frequently get this popup:



Of course, you want to click Continue so it completes but you'll also also want to see future LEGIT warnings too.  Mozilla folks should look into not displaying fake "unresponsive script" messages when the program is indeed actively moving the emails just fine.   This is too unnerving and a bug!