No tab drag and drop. It's an essential feature of any browser and there is no excuse for it, as it's unobtrusive and UX 101. Had me speechless coming back to firefox after a while and seeing they intentionally removed this, and consistently held back the thousands upon thousands of requests both in github and reddit across THREE YEARS. All request threads are closed without even acknowledgement of this being an issue. What a disgrace in the open source community. And this is just one issue.