It would be helpful to add a space after the path when you drag in a file or directory. This makes it much easier to enter a command and then drag in two files/dirs as the two arguments without needing to type a space in between, such as when diffing two files or using rsync to copy one directory to another. Other terminals I tried do this: GNOME Terminal, MATE Terminal (both with the same VTE as Xfce-terminal), KDE's Konsole and MacOS's Terminal.
Igor referenced this bugreport in commit ce8193242e73650856243c5714f8a827dc85eb63 Add a space character after a dragged filename or URL https://git.xfce.org/apps/xfce4-terminal/commit?id=ce8193242e73650856243c5714f8a827dc85eb63
Fixed, thanks!