Sawfish and dual head : state of the art

[Jerome <j-andrieux laposte net>]

It's quite difficult to find any information on the net about dual
screen handling with X in general.
One would easily find how to set up a dual screen config in
/etx/X11:XF86Config-4 but what about WMs ?
I'd like to gather feelings about this, so that I could write some doc
and submit it. 

Sawfish offers 3 (2) ways to handle dual head setup :
. sawfish --multihead :
	obsolete, bloated, you're told not to do this if you don't want to
	lose your ~/.sawfish/ :/
	I don't really know if this is truth or fud, however it makes it
	possible to run 2 different SF on both heads.
	The SF are *really* independent, and you can't move a window from a
	head to the other. Some objects like files in file managers might
	move, useless-drag-n-drop-thingie-that-just-works (tm).
	Quite difficult to switch from one display to the other.
	Ex: your mail/irc client, monitoring apps, all you need to keep an
	eye on, on 1 and the rest on the other.
	Very pratical for monitoring-like tasks.

. sawfish & DISPLAY=:0.1 sawfish in .xinitrc :
	exactly the same as above.

. startx -- +xinerama and sawfish in .xinitrc :
	Your two+ head are now a huge composite desktop, sawfish is running 
	on it as on a single head.
	You can drag n drop / move windows from a head to the other.
	You can cycle between windows on the two heads.
	Ex: Editor running on 1 and the result (pdf for latex,
	applications when coding, etc) on the other. 
	Pratical to get extended thematic workspaces, 

*XINERAMA*

Let's consider this setup (I tried not to use tabs, so it should display
nicely) :

         ________________________________
        |             |                  |
        |             |                  |
        |             |                  |
        |      1      |        2         |
        |             |                  |
        |_____________|                  |
                      |                  |
                      |                  |
                      |__________________|

Head 1 : 1024x768     (Laptop monitor)
Head 2 : 1280x1024     (external LCD)

*placement*
Sawfish understands this setup as a large (1024+1280)x(1024) desktop and
not really a composite.
The main side effect is that some window are misplaced :

         ________________________________
        |             |                  |
        |             |                  |
        |             |                  |
        |      1      |        2         |
        |  ____       |                  |
        |_| w  |______|                  |
          |____|      |                  |
                      |                  |
                      |__________________|

Sawfish seems to understand the space below 1 as free space and place
windows on it.

*borders*
The limit between 1 and 2 is quite problematic. No window are initially
drawn by SF on this limit however many apps are started in a very large
mode, so that they cross the limit. 

-- 
Jérôme