Subject: FVWM: on Rasterman comments about lastX

From: [email-masked]
Date: Fri, 19 Jan 2001 16:31:53 -0500

On 16(?) Jan, [email-masked] answered:

> EWWWWWWWWWWWWWWWWW! I read your html description. ewwwwwwwwwww! xwd and
> xwud? You're not serious? you do realise that closing a window now
> involves:
> 1. a read from the framebuffer across the bus to system memory - this
> is already an order of 10 times slower than writes and should be avoided
> at all costs.

You are right. Speed is a most basic concern in initiating and running any
process. However, this should not be an issue when it comes to end it,
since -by definition- we are no more interested in its speed.

A different thing would be its impact on the speed of management of the
rest of the processes-windows:
Do you mean the consumption of bus bandwith would be important?
Keep in mind that -most probably- what the user is looking at that moment
is precisely at the window he-she is closing.

>
> 2. a write to disk of a reasonable chunk of data
> 3. no ability to get the program back in an active state.
>
> 3 is basically impossible anyway (due to the way things work - when you
> "close" a window the wm sends the app a message saying "the user wants
> to close you" - the app now can respond any way it likes - either just
> exit - thus the window vanishes one way or another, or it can put up
> dialogs saying "are you sure" etc. or not respond at all and stay up if
> it doesn't want to quit. there are ways of "killing" the window - but
> this is rather nasty if the app is already advertising that it wants not
> b asked to quit.
>
> 2 could be avoided and 1 could be minimised if the contents of the
> window were held as a pixmap in the server - if you have spare video
> ram the pixmap may stay completely within video memory thus bypassing
> having to read across the bus -  anfd we already bypass the write
> to/read from disk. this of course means u need a program t maintain the
> pixmaps (probably the wm) so u can get them back too.

2. A write to disk is the only way to free valuable RAM from data that
-hopefully- will rarely be needed again, so doesn't have to be kept at hand.
At this point we have to make a vote of confidence that the operating
system has optimized disk management, so reads and writes are done without
overall impact.

Using xwd additionally ensures the size of the window will not surpass the
screen ("desktop") size, securely limiting the chunk of data to some 1.5 MB
(for a fullscreen 1024x768x32 window).

3. Popup dialogs do not interfere, as long as they are answered, not closed
(in which case THEY are the last window closed).

Windows that refuse to close are neither a problem:
If they are still there, they obviously don't need to be recovered. :)
Anyway, if you prefer, just replace the title 'last X closed' by the more
correct 'last window ordered to close'.

>
> but still - i wonder how really useful it is to just get an image of
> your last apps state and not have it active at all...?

As you correctly pointed out, that is basically impossible (at least without
changing the kernel profoundly).
Although a similar window could be optionally started in the same position
running the same application (like Enlightenment does at restoring a user's
session) there is no need for any "lastX" in order to do that:
it would suffice to just re-invoke that specific application.

In other words: what you really want is the image of its last state,
and only secondarily the option to reinitiate the process.

> --
> --------------- Codito, ergo sum - "I code, therefore I am"
>

This one is much better:
--------------- Cogito, ergo sum.  "I think, therefore I am."

It is often easier to code things oneself than going through the mess of
information to see if there is already an application or library that
does the same thing.

I however force myself to use already-made tools. A lot can be learned
in doing so. Additionally, it keeps me from reinventing the wheel.

This led me, for instance, to get knowing fvwm2, a window manager so small
that not even the way of closing a window is written in its code.

No, I am not recommending you to use fvwm2, but just give lastX a try to
see it in action: You can not imagine how spectacular it really is.
After all, think that you have already undergone the worst part:
understanding the instructions.

Useful?
Many would question even wether a window system is.

Thank you for the in-depth analysis.

Juanjo.
[email-masked]

__________________________________________________________________
Get your own FREE, personal Netscape Webmail account today at http://webmail.netscape.com/
--
Visit the official FVWM web page at <URL: http://www.fvwm.org/>.
To unsubscribe from the list, send "unsubscribe fvwm" in the body of a
message to [email-masked].
To report problems, send mail to [email-masked].