Дистрибутив Gentoo, Thunderbird-bin 38.6.0, при запуске создает каталог ~/Desktop:
read(23, "XDG_DESKTOP_DIR=\"$HOME\"\nXDG_DOCU"..., 4096) = 201
read(23, "", 4096) = 0
close(23) = 0
munmap(0x7f4d4fd2e000, 4096) = 0
access("/home/owl/Desktop", F_OK) = -1 ENOENT (No such file or directory)
mkdir("/home/owl/Desktop", 0755) = 0