Hello,
I could previously close folder tabs with the middle mouse button. But now I can't find the setting for this anymore. Does it still exist?
There's no setting for that, it's just always enabled. If it's not working it might be because your mouse isn't configured to send a middle button click (e.g. in Logitech software you often need to set it as a "generic button").
wow, that was fast. you're right. after i installed the logitech software, it will work again. thank you