-.SH COMMAND-LINE OPTIONS
-.I xscreensaver
-also accepts a few command-line options, mostly for use when debugging:
-for normal operation, you should configure things via the \fI~/.xscreensaver\fP
-file.
-.TP 8
-.B \-display \fIhost:display.screen\fP
-The X display to use. For displays with multiple screens, XScreenSaver
-will manage all screens on the display simultaniously.
-.TP 8
-.B \-verbose
-Same as setting the \fIverbose\fP resource to \fItrue\fP: print diagnostics
-on stderr and on the xscreensaver window.
-.TP 8
-.B \-no-capture-stderr
-Same as setting the \fIcaptureStderr\fP resource to \fIfalse\fP: do not
-redirect the stdout and stderr streams to the xscreensaver window itself.
-If xscreensaver is crashing, you might need to do this in order to see
-the error message.
-.SH HOW IT WORKS
-When it is time to activate the screensaver, a full-screen black window is
-created on each screen of the display. Each window is created in such a way
-that, to any subsequently-created programs, it will appear to be a ``virtual
-root'' window. Because of this, any program which draws on the root
-window (and which understands virtual roots) can be used as a screensaver.
-
-When the user becomes active again, the screensaver windows are unmapped, and
-the running subprocesses are killed by sending them \fBSIGTERM\fP. This is
-also how the subprocesses are killed when the screensaver decides that it's
-time to run a different demo: the old one is killed and a new one is launched.
-
-Before launching a subprocess, \fIxscreensaver\fP stores an appropriate value
-for \fB$DISPLAY\fP in the environment that the child will receive. (This is
-so that if you start \fIxscreensaver\fP with a \fI-display\fP argument, the
-programs which \fIxscreensaver\fP launches will draw on the same display;
-and so that the child will end up drawing on the appropriate screen of a
-multi-headed display.)
-
-When the screensaver turns off, or is killed, care is taken to restore
-the ``real'' virtual root window if there is one. Because of this, it is
-important that you not kill the screensaver process with \fIkill -9\fP if
-you are running a virtual-root window manager. If you kill it with \-9,
-you may need to restart your window manager to repair the damage. This
-isn't an issue if you aren't running a virtual-root window manager.
-
-For all the gory details, see the commentary at the top of xscreensaver.c.
-
-You can control a running screensaver process by using the
-.BR xscreensaver\-command (1)
-program (which see.)
-.SH POWER MANAGEMENT
-Modern X servers contain support to power down the monitor after an idle
-period. If the monitor has powered down, then \fIxscreensaver\fP will
-notice this (after a few minutes), and will not waste CPU by drawing
-graphics demos on a black screen. An attempt will also be made to
-explicitly power the monitor back up as soon as user activity is detected.
-
-As of version 3.28 (Feb 2001), the \fI~/.xscreensaver\fP file controls the
-configuration of your display's power management settings: if you have
-used
-.BR xset (1)
-to change your power management settings, then xscreensaver will
-override those changes with the values specified
-in \fI~/.xscreensaver\fP (or with its built-in defaults, if there
-is no \fI~/.xscreensaver\fP file yet.)
-
-To change your power management settings, run
-.BR xscreensaver\-demo (1)
-and change the various timeouts through the user interface.
-Alternately, you can edit the \fI~/.xscreensaver\fP file directly.
-
-If the power management section is grayed out in the
-.BR xscreensaver\-demo (1)
-window, then that means that your X server does not support
-the XDPMS extension, and so control over the monitor's power state
-is not available.
-
-If you're using a laptop, don't be surprised if changing the DPMS
-settings has no effect: many laptops have monitor power-saving behavior
-built in at a very low level that is invisible to Unix and X. On such
-systems, you can typically adjust the power-saving delays only by
-changing settings in the BIOS in some hardware-specific way.
-
-If DPMS seems not to be working with XFree86, make sure the "DPMS"
-option is set in your \fI/etc/X11/XF86Config\fP file. See the
-.BR XF86Config (5)
-manual for details.
-.SH USING XDM(1)
-You can run \fIxscreensaver\fP from your
-.BR xdm (1)
-session, so that the screensaver will run even when nobody is logged
-in on the console.
-
-The trick to using xscreensaver with \fIxdm\fP is this: keep in mind the
-two very different states in which xscreensaver will be running:
-.RS 4
-.TP 3
-.B 1: Nobody logged in.
-
-If you're thinking of running xscreensaver from XDM at all, then it's
-probably because you want graphics demos to be running on the console
-when nobody is logged in there. In this case, xscreensaver will function
-only as a screen saver, not a screen locker: it doesn't make sense
-for xscreensaver to lock the screen, since nobody is logged in yet!
-The only thing on the screen is the XDM login prompt.
-.TP 3
-.B 2: Somebody logged in.
-
-Once someone has logged in through the XDM login window, the situation is
-very different. For example: now it makes sense to lock the screen (and
-prompt for the logged in user's password); and now xscreensaver should
-consult that user's \fI~/.xscreensaver\fP file; and so on.
-.RE
-
-The difference between these two states comes down to a question of,
-which user is the \fIxscreensaver\fP process running as? For the first
-state, it doesn't matter. If you start \fIxscreensaver\fP in the usual
-XDM way, then xscreensaver will probably end up running as root, which
-is fine for the first case (the ``nobody logged in'' case.)
-
-However, once someone is logged in, running as root is no longer fine:
-because xscreensaver will be consulting root's \fI.xscreensaver\fP file
-instead of that of the logged in user, and won't be prompting for the
-logged in user's password, and so on. (This is not a security problem,
-it's just not what you want.)
-
-So, once someone has logged in, you want xscreensaver to be running as that
-user. The way to accomplish this is to kill the old xscreensaver process
-and start a new one (as the new user.)
-
-The simplest way to accomplish all of this is as follows:
-.RS 4
-.TP 3
-.B 1: Launch xscreensaver before anyone logs in.
-
-To the file \fI/usr/lib/X11/xdm/Xsetup\fP, add the lines
-.EX
-xhost +localhost
-xscreensaver-command -exit
-xscreensaver &
-.EE
-This will run xscreensaver as root, over the XDM login window.
-Moving the mouse will cause the screen to un-blank, and allow the user
-to type their password at XDM to log in.
-.TP 3
-.B 2: Restart xscreensaver when someone logs in.
-
-Near the top of the file \fI/usr/lib/X11/xdm/Xsession\fP, add those same lines:
-.EX
-xscreensaver-command -exit
-xscreensaver &
-.EE
-When someone logs in, this will kill off the existing (root) xscreensaver
-process, and start a new one, running as the user who has just logged in.
-If the user's .xscreensaver file requests locking, they'll get it. They
-will also get their own choice of timeouts, and graphics demos, and so on.
-
-Alternately, each user could just put those lines in their
-personal \fI~/.xsession\fP files.
-.RE
-
-Make sure you have \fB$PATH\fP set up correctly in the \fIXsetup\fP
-and \fIXsession\fP scripts, or \fIxdm\fP won't be able to
-find \fIxscreensaver\fP, and/or \fIxscreensaver\fP won't be able to
-find its graphics demos.
-
-(If your system does not seem to be executing the \fIXsetup\fP file, you
-may need to configure it to do so: the traditional way to do this is
-to make that file the value of the \fIDisplayManager*setup\fP resource
-in the \fI/usr/lib/X11/xdm/xdm-config\fP file. See the man page for
-.BR xdm (1)
-for more details.)
-
-It is safe to run \fIxscreensaver\fP as root (as \fIxdm\fP is likely to do.)
-If run as root, \fIxscreensaver\fP changes its effective user and group ids
-to something safe (like \fI"nobody"\fP) before connecting to the X server
-or launching user-specified programs.
-
-An unfortunate side effect of this (important) security precaution is that
-it may conflict with cookie-based authentication.
-
-If you get "connection refused" errors when running \fIxscreensaver\fP
-from \fIxdm\fP, then this probably means that you have
-.BR xauth (1)
-or some other security mechanism turned on. One way around this is to
-add \fB"xhost\ +localhost"\fP to \fIXsetup\fP, just before \fIxscreensaver\fP
-is launched.
-
-Note that this will give access to the X server to anyone capable of logging
-in to the local machine, so in some environments, this might not be
-appropriate. If turning off file-system-based access control is not
-acceptable, then running \fIxscreensaver\fP from the \fIXsetup\fP file
-might not be possible, and xscreensaver will only work when running as
-a normal, unprivileged user.
-
-For more information on the X server's access control mechanisms, see the
-man pages for
-.BR X (1),
-.BR Xsecurity (1),
-.BR xauth (1),
-and
-.BR xhost (1).
-.SH USING GDM(1)
-Using xscreensaver with
-.BR gdm (1)
-is easy, because gdm has a configuration tool. Just fire up
-.BR gdmconfig (1)
-and on the \fIBackground\fP page, type \fB"xscreensaver -nosplash"\fP into
-the \fIBackground Program\fP field. That will cause gdm to run xscreensaver
-while nobody is logged in, and kill it as soon as someone does log in.
-(The user will then be responsible for starting xscreensaver on their
-own, if they want.)
-
-Another way to accomplish the same thing is to edit the
-file \fI/etc/X11/gdm/gdm.conf\fP to include:
-.EX
-BackgroundProgram=xscreensaver -nosplash
-RunBackgroundProgramAlways=true
-.EE
-In this situation, the \fIxscreensaver\fP process will probably be running
-as user \fIgdm\fP instead of \fIroot\fP. You can configure the settings
-for this nobody-logged-in state (timeouts, DPMS, etc.) by editing
-the \fI~gdm/.xscreensaver\fP file.
-.SH USING KDE (K DESKTOP ENVIRONMENT)
-I understand that KDE has invented their own wrapper around xscreensaver,
-that is inferior to
-.BR xscreensaver-demo (1)
-in any number of ways. I've never actually seen it, but I'm told that
-this is the way you disable it:
-.RS 4
-.TP 3
-\fB1: Switch off KDE's screen saver.\fP
-Open the ``\fIControl Center\fP'' and
-select the ``\fILook and Feel / Screensaver\fP'' page.
-Turn off the ``\fIEnable Screensaver\fP'' checkbox.
-.TP 3
-\fB2: Find your Autostart directory.\fP
-Open the ``\fILook and Feel / Desktop / Paths\fP'' page,
-and see what your ``Autostart'' directory is set to: it will
-probably be \fI~/.kde3/Autostart/\fP or something similar.
-.TP 3
-\fB3: Make xscreensaver be an Autostart program.\fP
-Create a file in your autostart directory
-called \fIxscreensaver.desktop\fP that contains the following five lines:
-.EX
-[Desktop Entry]
-Exec=xscreensaver
-Name=XScreensaver
-Type=Application
-X-KDE-StartupNotify=false
-.EE
-.RE
-.PP
-Now use xscreensaver normally, controlling it via the usual
-.BR xscreensaver-demo (1)
-and
-.BR xscreensaver-command (1)
-mechanisms.
-.SH USING CDE (COMMON DESKTOP ENVIRONMENT)
-The easiest way to use \fIxscreensaver\fP on a system with CDE is to simply
-switch off the built-in CDE screensaver, and use \fIxscreensaver\fP instead;
-and second, to tell the front panel to run
-.BR xscreensaver\-command (1)
-with the \fI\-lock\fP option when the \fILock\fP icon is clicked.
-
-To accomplish this involves five steps:
-.RS 4
-.TP 3
-\fB1: Switch off CDE's locker\fP
-Do this by turning off ``\fIScreen Saver and Screen Lock\fP'' in the
-Screen section of the Style Manager.
-.TP 3
-\fB2: Edit sessionetc\fP
-Edit the file \fI~/.dt/sessions/sessionetc\fP and add to it the line
-.EX
-xscreensaver &
-.EE
-And make sure the sessionetc file is executable.
-This will cause \fIxscreensaver\fP to be launched when you log in.
-(As always, make sure that xscreensaver and the graphics demos are on
-your \fB$PATH\fP; the path needs to be set in \fI.cshrc\fP
-and/or \fI.dtprofile\fP, not \fI.login\fP.)
-.TP 3
-\fB3: Create XScreenSaver.dt\fP
-Create a file called \fI~/.dt/types/XScreenSaver.dt\fP with the following
-contents:
-.EX
-ACTION XScreenSaver
-{
- LABEL XScreenSaver
- TYPE COMMAND
- EXEC_STRING xscreensaver-command -lock
- ICON Dtkey
- WINDOW_TYPE NO_STDIO
-}
-.EE
-This defines a ``lock'' command for the CDE front panel, that knows how
-to talk to \fIxscreensaver\fP.
-.TP 3
-\fB4: Create Lock.fp\fP
-Create a file called \fI~/.dt/types/Lock.fp\fP with the following
-contents:
-.EX
-CONTROL Lock
-{
- TYPE icon
- CONTAINER_NAME Switch
- CONTAINER_TYPE SWITCH
- POSITION_HINTS 1
- ICON Fplock
- LABEL Lock
- PUSH_ACTION XScreenSaver
- HELP_TOPIC FPOnItemLock
- HELP_VOLUME FPanel
-}
-.EE
-This associates the CDE front panel ``Lock'' icon with the lock command
-we just defined in step 3.
-.TP 3
-\fB5: Restart\fP
-Select ``\fIRestart Workspace Manager\fP'' from the popup menu to make
-your changes take effect. If things seem not to be working, check the
-file \fI~/.dt/errorlog\fP for error messages.
-.RE
-.SH USING HP VUE (VISUAL USER ENVIRONMENT)
-Since CDE is a descendant of VUE, the instructions for using xscreensaver
-under VUE are similar to the above:
-.RS 4
-.TP 3
-\fB1: Switch off VUE's locker\fP
-Open the ``\fIStyle Manager\fP'' and select ``\fIScreen\fP.''
-Turn off ``\fIScreen Saver and Screen Lock\fP'' option.
-.TP 3
-\fB2: Make sure you have a Session\fP
-Next, go to the Style Manager's, ``\fIStartup\fP'' page.
-Click on ``\fISet Home Session\fP'' to create a session, then
-on ``\fIReturn to Home Session\fP'' to select this session each
-time you log in.
-.TP 3
-\fB3: Edit vue.session\fP
-Edit the file \fI~/.vue/sessions/home/vue.session\fP and add to it
-the line
-.EX
-vuesmcmd -screen 0 -cmd "xscreensaver"
-.EE
-This will cause \fIxscreensaver\fP to be launched when you log in.
-(As always, make sure that xscreensaver and the graphics demos are on
-your \fB$PATH\fP; the path needs to be set in \fI.cshrc\fP
-and/or \fI.profile\fP, not \fI.login\fP.)
-.TP 3
-\fB3: Edit vuewmrc\fP
-Edit the file \fI~/.vue/vuewmrc\fP and add (or change) the Lock control:
-.EX
-CONTROL Lock
-{
- TYPE button
- IMAGE lock
- PUSH_ACTION f.exec "xscreensaver-command -lock"
- HELP_TOPIC FPLock
-}
-.EE
-This associates the VUE front panel ``Lock'' icon with the xscreensaver
-lock command.
-.RE
-.PP
-.SH BUGS
-Bugs? There are no bugs. Ok, well, maybe. If you find one, please let
-me know. http://www.jwz.org/xscreensaver/bugs.html explains how to
-construct the most useful bug reports.
-.TP 8
-.B Locking and XDM
-If xscreensaver has been launched from
-.BR xdm (1)
-before anyone has logged in, you will need to kill and then restart the
-xscreensaver daemon after you have logged in, or you will be confused by
-the results. (For example, locking won't work, and your \fI~/.xscreensaver\fP
-file will be ignored.)
-
-When you are logged in, you want the \fIxscreensaver\fP daemon to be
-running under \fIyour\fP user id, not as root or some other user.
-
-If it has already been started by \fIxdm\fP, you can kill it by sending
-it the \fBexit\fP command, and then re-launching it as you, by putting
-something like the following in your personal X startup script:
-.EX
-xscreensaver-command -exit
-xscreensaver &
-.EE
-The ``\fIUsing XDM(1)\fP'' section, above, goes into more detail, and explains
-how to configure the system to do this for all users automatically.
-.TP 8
-.B Locking and root logins
-In order for it to be safe for xscreensaver to be launched by \fIxdm\fP,
-certain precautions had to be taken, among them that xscreensaver never
-runs as \fIroot\fP. In particular, if it is launched as root (as \fIxdm\fP
-is likely to do), xscreensaver will disavow its privileges, and switch
-itself to a safe user id (such as \fInobody\fP.)
-
-An implication of this is that if you log in as \fIroot\fP on the console,
-xscreensaver will refuse to lock the screen (because it can't tell
-the difference between \fIroot\fP being logged in on the console, and a
-normal user being logged in on the console but xscreensaver having been
-launched by the
-.BR xdm (1)
-.I Xsetup
-file.)
-
-The solution to this is simple: you shouldn't be logging in on the console
-as \fIroot\fP in the first place! (What, are you crazy or something?)
-
-Proper Unix hygiene dictates that you should log in as yourself, and
-.BR su (1)
-to \fIroot\fP as necessary. People who spend their day logged in
-as \fIroot\fP are just begging for disaster.
-.TP 8
-.B XAUTH and XDM
-For xscreensaver to work when launched by
-.BR xdm (1),
-programs running on the local machine as user \fI"nobody"\fP must be
-able to connect to the X server. This means that if you want to run
-xscreensaver on the console while nobody is logged in, you may need
-to disable cookie-based access control (and allow all users who can log
-in to the local machine to connect to the display.)
-
-You should be sure that this is an acceptable thing to do in your
-environment before doing it. See the ``\fIUsing XDM(1)\fP'' section,
-above, for more details.
-.TP 8
-.B Passwords
-If you get an error message at startup like ``couldn't get password
-of \fIuser\fP'' then this probably means that you're on a system in which
-the
-.BR getpwent (3)
-library routine can only be effectively used by root. If this is the case,
-then \fIxscreensaver\fP must be installed as setuid to root in order for
-locking to work. Care has been taken to make this a safe thing to do.
-
-It also may mean that your system uses shadow passwords instead of the standard
-.BR getpwent (3)
-interface; in that case, you may need to change some options
-with \fIconfigure\fP and recompile.
-
-If you change your password after xscreensaver has been launched, it will
-continue using your old password to unlock the screen until xscreensaver
-is restarted. On some systems, it may accept \fIboth\fP your old and new
-passwords. So, after you change your password, you'll have to do
-.EX
-xscreensaver-command -restart
-.EE
-to make \fIxscreensaver\fP notice.
-.TP 8
-.B PAM Passwords
-If your system uses PAM (Pluggable Authentication Modules), then in order
-for xscreensaver to use PAM properly, PAM must be told about xscreensaver.
-The xscreensaver installation process should update the PAM data (on Linux,
-by creating the file \fI/etc/pam.d/xscreensaver\fP for you, and on Solaris,
-by telling you what lines to add to the \fI/etc/pam.conf\fP file.)
-
-If the PAM configuration files do not know about xscreensaver, then
-you \fImight\fP be in a situation where xscreensaver will refuse to ever
-unlock the screen.
-
-This is a design flaw in PAM (there is no way for a client to tell the
-difference between PAM responding ``I have never heard of your module,''
-and responding, ``you typed the wrong password.'') As far as I can tell,
-there is no way for xscreensaver to automatically work around this, or
-detect the problem in advance, so if you have PAM, make sure it is
-configured correctly!
-.TP 8
-.B Colormap lossage: TWM
-The \fBinstallColormap\fP option doesn't work very well with the
-.BR twm (1)
-window manager and its descendants, on 8-bit screens.
-
-There is a race condition between the screensaver and this window manager,
-which can result in the screensaver's colormap not getting installed
-properly, meaning the graphics hacks will appear in essentially random
-colors. (If the screen goes white instead of black, this is probably why.)
-
-The
-.BR mwm (1)
-and
-.BR olwm (1)
-window managers don't have this problem. The race condition exists
-because X (really, ICCCM) does not provide a way for an OverrideRedirect
-window to have its own colormap, short of grabbing the server (which is
-neither a good idea, nor really possible with the current design.) What
-happens is that, as soon as xscreensaver installs its colormap, \fBtwm\fP
-responds to the resultant \fBColormapNotify\fP event by re-instaling the
-default colormap. Apparently, \fBtwm\fP doesn't \fIalways\fP do this; it
-seems to do it regularly if the screensaver is activated from a menu item,
-but seems to not do it if the screensaver comes on of its own volition, or
-is activated from another console.
-.RS 8
-.TP 4
-.B Attention, window manager authors!
-You should only call
-.BR XInstallColormap (3)
-in response to user events. That is, it is appropriate to install a colormap
-in response to \fBFocusIn\fP, \fBFocusOut\fP, \fBEnterNotify\fP,
-and \fBLeaveNotify\fP events; but it is not appropriate to call it in
-response to \fBColormapNotify\fP events. If you install colormaps in
-response to \fIapplication\fP actions as well as in response to \fIuser\fP
-actions, then you create the situation where it is impossible for
-override-redirect applications (such as xscreensaver) to display their
-windows in the proper colors.
-.RE
-.TP 8
-.B Colormap lossage: XV, XAnim, XEarth
-Some programs don't operate properly on visuals other than the default one,
-or with colormaps other than the default one. See the discussion of the
-magic "default-n" visual name in the description of the \fBprograms\fP
-resource in the \fIConfiguration\fP section. When programs only work with
-the default colormap, you need to use a syntax like this:
-.EX
- default-n: xv -root image-1.gif -quit \\n\\
- default-n: xearth -nostars -wait 0 \\n\\
-.EE
-It would also work to turn off the \fBinstallColormap\fP option altogether,
-but that would deny extra colors to those programs that \fIcan\fP take
-advantage of them.
-.TP 8
-.B Machine Load
-Although this program ``nices'' the subprocesses that it starts,
-graphics-intensive subprograms can still overload the machine by causing
-the X server process itself (which is not ``niced'') to consume many
-cycles. Care has been taken in all the modules shipped with xscreensaver
-to sleep periodically, and not run full tilt, so as not to cause
-appreciable load.
-
-However, if you are running the OpenGL-based screen savers on a machine
-that does not have a video card with 3D acceleration, they \fIwill\fP
-make your machine slow, despite
-.BR nice (1).
-
-Your options are: don't use the OpenGL display modes; or, collect the
-spare change hidden under the cushions of your couch, and use it to
-buy a video card manufactured after 1998. (It doesn't even need to be
-\fIfast\fP 3D hardware: the problem will be fixed if there is any
-3D hardware \fIat all.\fP)
-.TP 8
-.B XFree86's Magic Keystrokes
-The XFree86 X server traps certain magic keystrokes before client programs ever
-see them. Two that are of note are Ctrl+Alt+Backspace, which causes
-the X server to exit; and Ctrl+Alt+F\fIn\fP, which switches virtual consoles.
-The X server will respond to these keystrokes even if xscreensaver has the
-screen locked. Depending on your setup, you might consider this a problem.
-
-Unfortunately, there is no way for xscreensaver itself to override the
-interpretation of these keys. If you want to disable Ctrl+Alt+Backspace
-globally, you need to set the \fIDontZap\fP flag in
-your \fI/etc/X11/XF86Config\fP file. To globally disable VT switching,
-you can set the \fIDontVTSwitch\fP flag. See the
-.BR XF86Config (5)
-manual for details.
-.TP 8
-.B MIT Extension and Fading
-The \fBMIT-SCREEN-SAVER\fP extension is junk. Don't use it.
-
-When using the \fBMIT-SCREEN-SAVER\fP extension in conjunction with
-the \fBfade\fP option, you'll notice an unattractive flicker just before
-the fade begins. This is because the server maps a black window just before
-it tells the \fIxscreensaver\fP process to activate. The \fIxscreensaver\fP
-process immediately unmaps that window, but this results in a flicker. I
-haven't figured a way to get around this; it seems to be a fundamental
-property of the (mis-) design of this server extension.
-
-It sure would be nice if someone would implement the \fBSGI SCREEN_SAVER\fP
-extension in XFree86; it's dead simple, and works far better than the
-overengineered and broken \fBMIT-SCREEN-SAVER\fP extension.
-.TP 8
-.B Keyboard LEDs
-If \fIprocInterrupts\fP is on (which is the default on Linux systems) and
-you're using some program that toggles the state of your keyboard LEDs,
-xscreensaver won't work right: turning those LEDs on or off causes a
-keyboard interrupt, which xscreensaver will interpret as user activity.
-So if you're using such a program, set the \fIprocInterrupts\fP resource
-to False.
-.TP 8
-.B Extensions
-If you are not making use of one of the server extensions (\fBXIDLE\fP,
-\fBSGI SCREEN_SAVER\fP, or \fBMIT-SCREEN-SAVER\fP), then it is possible, in
-rare situations, for \fIxscreensaver\fP to interfere with event propagation
-and make another X program malfunction. For this to occur, that other
-application would need to \fInot\fP select \fBKeyPress\fP events on its
-non-leaf windows within the first 30 seconds of their existence, but then
-select for them later. In this case, that client \fImight\fP fail to receive
-those events. This isn't very likely, since programs generally select a
-constant set of events immediately after creating their windows and then
-don't change them, but this is the reason that it's a good idea to install
-and use one of the server extensions instead, to work around this shortcoming
-in the X protocol.
-
-In all these years, I've not heard of even a single case of this happening,
-but it is theoretically possible, so I'm mentioning it for completeness...