I've recently upgraded to Thunderbird 60.3.3 Now if I detach an attachment from an email the confirmation window pops up on the very bottom of of the thunderbird window and is almost hidden - see screendump. After I resize the thunderbird window the confirmation window jumps to somewhere in the middle. This doesn't happen every time I detach an attachment. Maybe after I once resized thunderbird window the pop up is no more hidden even if I change the size back. I use thunderbird on macOS 10.14.2 (18C54)