XDM, GDM, KDM, WDM shootout :-)

[Osamu Aoki <osamu@debian.org>]

Hi, this is FYI.

I made a comparison of 4 main display managers in Debian (unstable): 
  * XDM - the good old one
  * GDM - the Gnome one
  * WDM - the WindowMaker one
  * KDM - the KDE one

The result of comparison is (+ is yes, - is no):

         1) Use of      2) Choice  3) Choice     4) Customized  5) User
            Xsession.d     of WM      of Locale     Startup        List
  XDM       ++             --         --            ++             -
  GDM       +              +          ++            some alt.      ++
  KDM       --             +          --            custom         ++
  WDM       ++             +-         --            --             -
  
Conclusion:

  In short, for most cases GDM seems to be the best :-)

  Also, I realized as CJK user that there is no standard way to set up
  start up script under menu chosen WM.  This is major problem for CJK
  user who needs to set up keyboard input set up (sometimes daemon).  I
  hear that Mandrake uses ~/.i18n and SUSE uses ~/.xim.  There is no
  hook script in /etc/X11/Xsession.d/ to read this kind of files.
  Something needs to be done.

Here, the verbose meaning of above comparison are:
  1) Use of /etc/X11/Xsession.d/
  2) Choice of session/window manager by menu
  3) Choice of locales by menu
  4) Customizable start up like ~/.xsession
  5) User list (if customized, default can be on/off)
======================================================================
Detailed review results.

* XDM: Simplest, light and works.

  This is reference DM.  Not much menu as expected.  

* GDM: The best of all and flashy graphics (even for KDE).

  Its start up script does not call /etc/X11/Xsession, but practically
  the same code with GDM specific enhancement is executed to run scripts
  in /etc/X11/Xsession.d/.
  
  For the choice of WM, I did not see xfce.  But it was OK.
  
  For custom startup, ~/.gnomerc is run.  This is only for
  gnome-session.  Although custom mode should run ~/.xsession, I do not
  see custom in menu.  Besides, use of ~/.xsession by its nature
  override menu selected WM.  For non gnome-session, I do not see easy
  way to provide user customization with default install. 
  
  Default start mode is user selectable. (Can be annoying)
  
  Linked to gnome and many library.  Can be heavy.

* KDM: Good but why strange startup?

  Its start up script does not call /etc/X11/Xsession nor bother to use
  /etc/X11/Xsession.d/.  Thus out of lack with ssh-agent. (Bug #265865)
  
  Locale choice does not exist.
  
  Custom mode should run ~/.xsession.  
  
  Default is always KDE.

* WDM: Simple but gives you choice of WM

  For the choice of WM, I saw false listing of metacity which itself is
  useless.  But it was OK.
  
  Locale choice does not exist.
  
  It looks lightest as WM selectable DM.

* General
  It looks like auto listing of available WM are tricky.  Despite some
  glitches I saw, it was usable.  I think if there is a standard way to
  list available session manager / display manager, it can be better, I
  think.

-- 
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        Osamu Aoki <osamu@debian.org>  Brussels Belgium, GPG-key: A8061F32
 .''`.  Debian Reference: post-installation user's guide for non-developers
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