Drag support from thunderbird to firefox has stopped working recently(I mean drag a file to upload in some website for example onedrive or web whatsapp or web telegram) in my windows machine. It was not totally relieble before but at least with a few tries I could do it. I thoutgh that the problem was in the website that I was using. But it appears that the problem resides on thunderbird or firefox because in my Linux machine I have been able to drag in from thunderbird to firefox without problems at all.
On another side I have been testing, thunderbird appear to upload without problems files to edge or file explorer, in addition firefox accepts files from the explorer without problems too. And I have been testing with a totally new profile on both, thunderbird and firefox to see if there was problems from some user config.
To sum up, on windows, firefox accepts files from explorer, explorer and MS edge accepts files from thunderbird but directly from thunderbird to firefox is not possible since some update I suppose, before was working but not totally relieble. In Linux I have not problems with wayland enabled on both sides. If you need something more tell me, but I think you shoul reproduce this without problems... It's windows+empty profiles on both sides, thunderbird and firefox...
