Subject: FVWM: fvwm, SuSE, backing store

From: Lucio Chiappetti <[email-masked]>
Date: Fri, 27 May 2005 15:43:01 +0200 (CEST)

Having recently moved from Alpha to SuSE Linux (using fvwm as window 
manager, but kdm to start X as default with SuSE [9.2]) I've noticed a 
funny behaviour in some applications :

(1) RSI IDL plot windows seems not to have any backing store. When they
    are obscured I lose the obscured part, when I move them to another
    dekstop page I lose all.

    (on Alpha they used to behave like that only after several days the
    server was running, like it had exhausted backing store memory)

    NB xwininfo returns
    Backing Store State:  Always
    Save Under State: no

(2) a small application of mine (Fortran wrapped around C Xlib calls)
    has a similar behaviour (on Alpha it did work). Windows are created
    with

     flag=CWBitGravity|CWWinGravity|CWBackingStore;
     XChangeWindowAttributes(dpy,win,flag,&attrib);

(3) the Hessling editor (the) in Xcurses mode sometimes presents a
    problem (when I do a large mouse cut-an-paste it hangs, and then if I
    obscure part of the edit window it remains white and deprived of
    textual content).

    This behaviour occurred also (more frequently) on Alpha and is
    possibly unrelated with the other two (looks more an overflow of
    the clipboard)

    Anyhow xthe windows return to xwininfo

    Backing Store State: NotUseful
    Save Under State: no

    which is also what xterm or rxvt do (and they work)

Now I wonder whether this has anything to do with fvwm or with the X 
server. I tried adding this to my .fvwmrc, but with no effect

Style * BackingStore
Style * SaveUnder

I have no idea of how to check whether backing store is enabled in the X 
server. It looks like the server runs as 

/usr/X11R6/bin/X -nolisten tcp -br vt7 -auth blabla

but some of those options are undocumented in the X man page (and it does 
not mention backing store).

Any clue ?

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Lucio Chiappetti - INAF/IASF - via Bassini 15 - I-20133 Milano (Italy)
For more info : http://www.mi.iasf.cnr.it/~lucio/personal.html
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---

From: Dan Espen <[email-masked]>
Date: Fri, 27 May 2005 19:05:14 -0400

> server. It looks like the server runs as 

Check this way:

  xdpyinfo | grep back      
  options:    backing-store NO, save-unders NO

The last time I tried running with it on,
everything seemed to slow down.

To turn it on, it your Xorg.conf file add to the Device
section:

    Option "BackingStore" "True"
    Option "SaveUnders" "True"

> not mention backing store).

It should be documented in 'man xorg.conf' but I don't see it there.

-- 
Dan Espen                           E-mail: [email-masked]

---

From: Rainer Koehler <[email-masked]>
Date: Mon, 30 May 2005 14:46:31 +0200

>     Backing Store State:  Always

I've used IDL on Solaris and Linux, and I always had to tell it to use
it's own backing store by putting "device,retain=2" into its
startup-file.  The documentation says the default is to request the
server to do it, but that doesn't work.  BTW, you have to set it
before you open any IDL-windows.

Don't know if it has anything to do with FVWM, I don't use other
window managers :-)

HTH,
Rainer

---

From: Lucio Chiappetti <[email-masked]>
Date: Mon, 30 May 2005 19:14:58 +0200 (CEST)

I asked about missing backing store for some application windows under 
FVWM under Linux SuSE. It looks like it is not a FVWM issue but an Xserver 
issue.

First of all Dan Espen suggested a way to check whether the server has it
 
>   options:    backing-store NO, save-unders NO
 
Then Rainer Koehler commented about one specific application (RSI IDL)
 
> startup-file.  

I discovered the RETAIN option of IDL myself looking in the manual (but my 
experience on Digital Unix and Solaris was that the system WAS providing 
backing store so I never needed it before).

That would fix this single application nicely. It won't fix a less modern 
application of mine which relies on the server.

The clue came again from Dan Espen :

> To turn it on, it your Xorg.conf file add to the Device section:
>

I read again the xorg.conf, X and also Xorg and Xservers man pages, and 
they are not so explicit or clear about this option, but apparently 
putting the first of the two options in /etc/X11/xorg,conf (if SuSE won't 
overwrite it next time) does the trick for all applications. I tried also 
with both options, and it works too, but the second one is apparently 
unnecessary (the xorg log file says "not used").

I'll try to leave it turned on and see whether I notice performance 
degradation (so far not).

----------------------------------------------------------------------------
Lucio Chiappetti - INAF/IASF - via Bassini 15 - I-20133 Milano (Italy)
----------------------------------------------------------------------------
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mezzo di risoluzione delle controversie  way of resolution of  international
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                [Art. 11 Constitution of the Italian Republic]
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