b2b17b2c_6_6__The_X_Display_Manager__Description
[File] Xresources [Description] 
This file controls the look and feel of the XDM display chooser and login screens. The default configuration is a simple rectangular login window with the hostname of the machine displayed at the top in a large font and “Login:” and “Password:” prompts below. The format of this file is identical to the app-defaults file described in the Xorg documentation.
6.6. The X Display Manager
Description