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middleclick-autoscroll/doc/middleclick-autoscroll.1.scd
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Felitendo dcdf2c1df3 fix: never leave Steam a file it would reinstall itself over
The patch that keeps the script's length was the good path and appending was
the fallback, with -noverifyfiles on everything that starts Steam to cover for
it. That cover does not exist.

Steam checks its files at the shutdown it runs itself, not only at a start
somebody handed arguments to, and that run carries no -noverifyfiles whatever
the session was started with. One wrong length there costs the whole client
package downloaded, extracted and installed again - and the client quits at the
end of it instead of coming up, which is the "Steam just closed itself" that
this was seen as:

    BVerifyInstalledFiles: steamwebhelper.sh is 130 bytes, expected 84
    Update wird heruntergeladen ... Paket wird extrahiert ...
    Aktualisierung abgeschlossen, Steam wird geladen ... Shutdown

So the flag now either fits in the space the comments give back or it is not
written at all, and the status screen says Steam is not patched. No autoscroll
in the interface is a far smaller thing than a client that reinstalls itself.

With no growing patch left to prop up, -noverifyfiles has nothing to do and is
gone with everything that carried it: Steam's launcher entry, its autostart
entry, the shortcuts on the desktop and the ones it writes for single games.
Steam repairs its own installation again. An installation from an older version
is taken back once through the flag scheme, and a patch that version appended
is rebuilt to fit at the next apply - or taken back, if the comments cannot pay
for it.
2026-09-05 01:07:15 +02:00

216 lines
8.9 KiB
Scdoc

middleclick-autoscroll(1)
# NAME
middleclick-autoscroll - middle-click autoscroll in every application that supports it
# SYNOPSIS
*middleclick-autoscroll* [_command_]
# DESCRIPTION
Blink, the engine inside Chromium, Electron and CEF, implements Windows-style
autoscroll: hold the middle mouse button and the page scrolls with the pointer.
On Linux it is switched off, because middle click is taken by primary-selection
paste. It can be turned back on with *--enable-blink-features=MiddleClickAutoscroll*
on the command line.
*middleclick-autoscroll* finds every Chromium-based application on the system
and puts that argument somewhere the application will actually read it, then
keeps doing so for anything installed later.
A browser is given *--enable-features=MiddleClickAutoscroll* instead. It asks
for the same feature - Blink generates a feature of that name for each of its
runtime flags - but it is not on the list of flags Chromium warns about, so the
browser does not put a bar reading "You are using an unsupported command-line
flag" above every page. That spelling only works from Chromium 124 onwards,
which is why everything else keeps the first one: an application that embeds an
older Chromium, such as Steam's CEF, has no such bar to show anyway. Helium
knows the feature under a name of its own and is asked for
*HeliumMiddleClickAutoscroll* as well; a name a browser does not know is
ignored. It works on any distribution:
which of the routes below an application takes is read off its launcher, not
assumed from where the launcher came from.
Run without a command it shows an interactive menu. Everything it can be told
is reachable from there; the configuration file behind it does not need to be
edited by hand.
Nothing outside the user's home directory is written to, and running it as root
is refused.
# COMMANDS
*enable*
Turn autoscroll on, apply it to everything installed, and start watching
for new applications.
*disable*
Turn it off and put every file that was changed back the way it was.
*apply* [*--rebuild*]
Apply to anything that has appeared since the last run. This is what the
watcher calls; running it by hand is only needed when the watcher is off.
Entries left behind by an application that has since been uninstalled are
removed here too - the entry shadowing it lives in the user's home, where
the package manager that removed the application cannot see it.
With *--rebuild* everything is taken back first and written again from
scratch. That is the repair: it does not care what looks correct already.
*status*
How many applications are covered, whether Steam is patched, and when the
last run was.
*list*
Every Chromium-based application that was found, and how each one is
handled.
*-h*, *--help*
Show a summary of the commands.
*-V*, *--version*
Show the version.
# HOW THE ARGUMENT GETS IN
Two ways, chosen per application.
*Flag file*
Where the launcher reads extra arguments from
_$XDG_CONFIG_HOME/<name>-flags.conf_. This is the preferred route: it is
the supported way to pass arguments, it survives package upgrades, and it
applies to a launch from a terminal as much as one from the menu. A
feature list that is already in the file is extended rather than
duplicated - Chromium keeps only the last occurrence of such an option, so
a second one would switch the first one off.
Arch's Electron and Chromium packages all wrap their binaries this way, and
so do a number of individual vendors' launchers elsewhere. Whether a given
launcher does is read off the launcher itself, never assumed from the
distribution: only one that really names such a file takes this route.
*Desktop entry*
For applications that ship their own binary with no wrapper, and for
everything inside a Flatpak or a snap, a copy of the desktop entry with the
argument appended is written to _~/.local/share/applications_, where it
shadows the system one. Entries that already live there - AppImages, web
app shortcuts - are edited in place, with the original kept.
This is the route everything takes on the distributions whose Chromium
wrappers keep their equivalent file under _/etc_, where it is the system's
to write and not the user's: Debian, Ubuntu, Fedora and openSUSE among
them.
A generated entry is marked *X-MCA-Generated* and an entry edited in place
*X-MCA-Patched*. The two are never confused: the first is deleted when
undoing, the second is restored from its backup. An entry with neither
marker belongs to somebody else and is left alone.
Programs that start themselves at login write their own entry into
_~/.config/autostart_ pointing straight at their binary, bypassing the menu
entry entirely. Those are patched in place as well.
Shortcuts on the desktop itself are patched in place too. Nothing in the XDG
search path looks at that folder, so a shortcut that lives only there would
otherwise be invisible - and Steam puts one there for every game somebody asks
for a shortcut to. The folder's name is translated, and the name in use is read
from _~/.config/user-dirs.dirs_ rather than guessed; the watcher is told about
it in a drop-in written when autoscroll is turned on.
# STEAM
Steam's interface is CEF and supports the feature, but Steam builds the command
line for its web helper itself. The only way in is the script that starts the
helper, inside Steam's own installation:
~/.local/share/Steam/ubuntu12_64/steamwebhelper_sniper_wrap.sh
Where that installation is depends on how Steam was installed:
_~/.local/share/Steam_ for Valve's own package and Arch's,
_~/.steam/debian-installation_ for Debian's, and the private tree of the
sandbox for the Flatpak and the snap. All of them are looked at.
Steam compares the installed files against its manifest at every start - by
size and timestamp rather than by content - and restores whatever differs. So
the patch is written to look untouched: the bytes the argument costs are taken
back out of the script's own comments and the timestamp is put back afterwards,
leaving a file exactly as long and exactly as old as Steam left it. A client
that checks its files finds nothing to repair, and the argument survives
however Steam was started - from the menu, from a game shortcut, from a
launcher like Heroic or Lutris, from a terminal.
That is what has to work, because it is the only thing that does. A patch that
changes the length is never written, whatever else could be done to cover for
it: Steam checks its files at the shutdown it runs itself as well as at a start
it was given arguments for, and that one carries no arguments of anybody's. One
wrong length costs the whole client package downloaded, extracted and installed
again, and a client that quits at the end of it instead of coming up.
So where the comments cannot pay for the argument, or a client update has
changed how the helper is started, nothing is written and the status screen
says Steam is not patched. Nothing goes on Steam's launcher entry, its
autostart entry or the shortcuts it writes for single games either, and Steam
goes on repairing its own installation.
An installation patched by an earlier version, which appended where the
comments were short, is written again to fit at the next apply, or taken back
if it cannot be made to.
A client update brings a new version of the script. The watcher notices and
patches it again, and the copy kept for undoing is replaced with the new
version at the same time, so undoing puts back the script Steam last shipped
rather than the one from before the update.
# SPOTIFY
The official client is CEF rather than Electron. Installed through
*spotify-launcher*, it is started by a program that builds its own command line
and has a configuration file with a slot for extra arguments; that slot is
where the flag goes. Installed as a plain package, a Flatpak or a snap, it is
an ordinary desktop entry and needs nothing special.
# WHAT CANNOT BE DETECTED
An AppImage keeps its payload in a compressed filesystem, so there is no way to
tell from the outside whether it contains Chromium. Those are listed as *cannot
tell* and left alone until they are switched on from the applications screen.
# FILES
_~/.config/middleclick-autoscroll/config_
Written by the program. Every option in it is reachable from the menu.
_~/.local/state/middleclick-autoscroll/ledger_
One line per change, so *disable* can undo exactly what was done and
nothing else.
_~/.local/state/middleclick-autoscroll/backup/_
Copies of the files that are edited in place rather than shadowed.
_~/.cache/middleclick-autoscroll/detect_
Which programs were found to be Chromium, keyed by size and modification
time. Safe to delete.
# ENVIRONMENT
*NO_COLOR*
Disables colour.
# REQUIREMENTS
Bash 4.2 or newer and GNU coreutils. The watcher needs a systemd user session;
without one everything else works and applications installed later are picked
up at the next *apply* rather than on their own.
# SEE ALSO
*systemctl*(1), *flatpak*(1), *snap*(8)
# AUTHORS
Felitendo. Source and issue tracker at
https://github.com/Felitendo/middleclick-autoscroll