The best feature I like about Arch Linux is that it can be freely customized. Previously, I was using LXDE on Arch Linux. Then I found some problem that when I want to change the desktop background mode, LXDE will be restarted immediately. This problem causes me fail to boot properly when I am upgrading the kernel. As a result, I need to downgrade the kernel to the previous one in order to boot properly.
Therefore, I tried to use Xfce, which is also a lightweight desktop environment. Unlike LXDE, Xfce does not has any display manager. So, I choose GDM, which is able to work with Xfce. Now, everything works fine. Good.