[CentOS] X11 virtual screens on centos 5

Mon Sep 17 01:48:33 UTC 2007
Ross S. W. Walker <rwalker at medallion.com>

William L. Maltby wrote:
> 
> On Tue, 2007-09-04 at 21:40 -0400, Jerry Geis wrote:
> > When the you select an X11 virtual screen (1 of 4) with the 
> mouse on 
> > default centos 5
> > what command gets executed to show screen 1, screen 2 etc...
> > 
> > Basically, I want to have a command or know the command
> > to     execute to show the desired virtual X11 screen.
> 
> I'm not knowledgeable about this specific topic, but the last 
> X question
> I saw got no response for over a week, so I thought I would jump in.
> That resulted in an immediate response by one who seems knowledgeable.
> Som *my* level of knowledge is not significant in that 
> scenario and may
> have value as an irritant.  :-)

It wasn't you that was irritant, but myself that was irritable. ;-)

> Regardless, it may be that question is so X-centric and CentOS-remote
> that few want to pursue it. Other lists/resources may be best.
> 
> Anyway, so, ...
> 
> It would surprise me if a "command to execute" exists. *Usually* these
> sort of things are internal responses to external 
> asynchronous events by
> the software that manages these resources. E.g., my mouse transitions
> from an active pane in X and enters a new one. Focus shifts 
> from the one
> being exited to the one being entered. Double-click the title bar and
> the application's pane is "rolled up" or "unrolled", etc.

Yes, these are controlled by the console driver or X. When at the text
console the console driver traps ALT-Fx and switches virtual screens
to the appropriate virtual terminal. When in X the X server traps
CTRL-ALT-Fx and switches control to the appropriate virtual terminal.

There exists a command-line command to do this as well, 'chvt' which
is part of the kbd package.

> For the specific task you mention, IIUC what you are asking, a <CTL>-
> <ALT>-<RIGHT|LEFT> is an event that also causes the switch to another
> screen. <CTL>-<ALT>-<TAB> rotates among desktop and panel focus, and
> <SHIFT>-<TAB> rotates focus through apps in a virtual desktop. IIUC,
> none of these things cause the loading or execution of some external
> program or command that can be invoked in a stand-alone mode.

These are handled by the window manager of choice, the X server only
traps CTRL-ALT-Fx, CTRL-ALT-BKSPC, CTRL-ALT-KEYPAD-ADD,
CTRL-ALT-KEYPAD-SUB, CTRL-ALT-KEYPAD-MUL, CTRL-ALT-KEYPAD-DIV.

> Given all that, if it is valid, your task would be to write a 
> small app
> for X that provides an "event" to which the existing 
> management software
> would respond. I hear that qt makes this easy... LOL! I'm 
> guessing that
> you want some automated way to cycle through screens? Maybe 
> that already
> exists and is locatable in google-land?

You can program a lot of powerful keyboard macros with KDE which aren't
set by default, I'd say you can do so in Gnome or XFCE, but I don't
know as I don't use those.

-Ross

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