source: trunk/third/metacity/README @ 18717

Metacity is not a meta-City as in an urban center, but rather
Meta-ness as in the state of being meta. i.e. metacity : meta as
opacity : opaque. Also it may have something to do with the Meta key
on UNIX keyboards.

The first release of Metacity was version 2.3. Metacity has no need for
your petty hangups about version numbers.

COMPILING METACITY
===

You need GTK+ 2.0, ideally the latest in the 2.0.x series.  For
multihead/Xinerama support to work, you need GTK+ 2.2.  For
startup notification to work you need libstartup-notification at
http://www.freedesktop.org/software/startup-notification/ or on the
GNOME ftp site. You also need GConf 1.2 (unless building a funky 
extra-small embedded metacity with --disable-gconf).

REPORTING BUGS AND SUBMITTING PATCHES
===

Report new bugs on http://bugzilla.gnome.org. Please check for
duplicates, *especially* if you are reporting a feature request. 

Please do *not* add "me too!" or "yes I really want this!" comments to
feature requests in bugzilla. Please read
http://pobox.com/~hp/features.html prior to adding any kind of flame
about missing features or misfeatures.

Feel free to send patches too; Metacity is relatively small and
simple, so if you find a bug or want to add a feature it should be
pretty easy.  Send me mail, or put the patch in bugzilla.

See the HACKING file for some notes on hacking Metacity.

SHRINKING METACITY
===

Not that metacity is huge (<400K binary last I checked), but about
half of that is in the preferences handling, in static strings that
aren't essential, and in the theme engine.

You can strip about 70K from the metacity binary by compiling with 
options such as:

 --disable-gconf
 --disable-sm
 --disable-verbose 
 --disable-startup-notification

However the result is no good for desktop use, all prefs have to be
hardcoded in the binary, for example. If you wanted to make a really
small metacity, here's some additional stuff you might consider
implementing:
 
 - add --disable-themes, which would replace theme.c and theme-parser.c 
   with a hardcoded implementation of the interface in theme.h, 
   should save about 80K. This should be fairly easy.

 - add --disable-gtk, which would implement the interface in ui.h
   without using GTK. This one is easier than you think because the
   main part of the window manager doesn't use GTK directly, but is
   still fairly hard to do.  You would probably have to give up some
   of the features, such as window menus, as menus are pretty complex
   to implement well.  So time may be better spent adding a GTK
   configure script feature to build GTK with only a small core set of
   functionality.

METACITY FEATURES
===

 - Boring window manager for the adult in you. Many window managers
   are like Marshmallow Froot Loops; Metacity is like Cheerios.

 - Uses GTK+ 2.0 for drawing window frames. This means colors, fonts, 
   etc. come from GTK+ theme.

 - Does not expose the concept of "window manager" to the user.  Some
   of the features in the GNOME control panel and other parts of the
   desktop happen to be implemented in metacity, such as changing your
   window border theme, or changing your window navigation shorcuts,
   but the user doesn't need to know this.

 - Includes only the window manager; does not try to be a desktop
   environment. The pager, configuration, etc. are all separate and
   modular. The "libwnck" library (which I also wrote) is available
   for writing metacity extensions, pagers, and so on. (But libwnck
   isn't metacity specific, or GNOME-dependent; it requires only GTK,
   and should work with KWin, fvwm2, and other EWMH-compliant WMs.)

 - Has a simple theme system and a couple of extra themes come with it.
   Change themes via gconf-editor or gconftool or GNOME themes control
   panel:
     gconftool-2 --type=string --set /apps/metacity/general/theme Crux
     gconftool-2 --type=string --set /apps/metacity/general/theme Gorilla
     gconftool-2 --type=string --set /apps/metacity/general/theme Atlanta
     gconftool-2 --type=string --set /apps/metacity/general/theme Bright

   See theme-format.txt for docs on the theme format. Use 
   metacity-theme-viewer to preview themes.

 - Change number of workspaces via gconf-editor or gconftool:
     gconftool-2 --type=int --set /apps/metacity/general/num_workspaces 5

   Can also change workspaces from GNOME 2 pager.

 - Change focus mode:
     gconftool-2 --type=string --set /apps/metacity/general/focus_mode mouse
     gconftool-2 --type=string --set /apps/metacity/general/focus_mode sloppy
     gconftool-2 --type=string --set /apps/metacity/general/focus_mode click

 - Global keybinding defaults include:   

    Alt-Tab                forward cycle window focus
    Alt-Shift-Tab          backward cycle focus
    Alt-Ctrl-Tab           forward cycle focus among panels
    Alt-Ctrl-Shift-Tab     backward cycle focus among panels
    Alt-Escape             cycle window focus without a popup thingy
    Ctrl-Alt-Left Arrow    previous workspace
    Ctrl-Alt-Right Arrow   next workspace
    Ctrl-Alt-D             minimize/unminimize all, to show desktop

   Change keybindings for example:

     unst gconftool-2 --type=string --set /apps/metacity/global_keybindings/switch_to_workspace_1 '<Alt>F1'
   
   Also try the GNOME keyboard shortcuts control panel, or
   gconf-editor.

   See metacity.schemas for all available bindings.

 - Window keybindings:

    Alt-space         window menu

    Mnemonics work in the menu. That is, Alt-space then underlined
    letter in the menu item works.

    Choose Move from menu, and arrow keys to move the window.

    While moving, hold down Control to move slower, and 
      Shift to snap to edges.

    Choose Resize from menu, and nothing happens yet, but 
      eventually I might implement something.

    Keybindings for things like maximize window, vertical maximize,
    etc. can be bound, but may not all exist by default. See
    metacity.schemas.

 - Window mouse bindings:

    Clicking anywhere on frame with button 1 will raise/focus window
    
    If you click a window control, such as the close button, then the 
     control will activate on button release if you are still over it
     on release (as with most GUI toolkits)

    If you click and drag borders with button 1 it resizes the window
    
    If you click and drag the titlebar with button 1 it moves the 
     window.

    If you click anywhere on the frame with button 2 it lowers the 
     window.

    If you click anywhere on the frame with button 3 it shows the 
     window menu.

    If you hold down Super (windows key) and click inside a window, it
     will move the window (buttons 1 and 2) or show menu (button 3).
     Or you can configure a different modifier for this.

    If you pick up a window with button 1 and then switch workspaces
     the window will come with you to the new workspace, this is 
     a feature copied from Enlightenment.

    If you hold down Shift while moving a window, the window snaps
     to edges of other windows and the screen.

 - Session management:

    Metacity connects to the session manager and will set itself up to
     be respawned. It theoretically restores sizes/positions/workspace
     for session-aware applications.

 - Metacity implements much of the new window manager spec from
   freedesktop.org
   (http://www.freedesktop.org/standards/wm-spec.html), and much of
   the ICCCM. But then there are parts of each that it doesn't
   implement, just because I haven't yet.

 - Uses Pango to render text, so has cool i18n capabilities. 
   Supports UTF-8 window titles and such.

 - There are simple animations for actions such as minimization, 
   to help users see what is happening. Should probably 
   have a few more of these and make them nicer.

 - if you have the proper X setup, set the GDK_USE_XFT=1 
   environment variable to get antialiased window titles.

 - considers the panel when placing windows and maximizing
   them.

 - handles the window manager selection from the ICCCM. Will exit if
   another WM claims it, and can claim it from another WM if you pass
   the --replace argument. So if you're running another
   ICCCM-compliant WM, you can run "metacity --replace" to replace it
   with Metacity.

 - does basic colormap handling

 - and much more! well, maybe not a lot more.

HOW TO ADD EXTERNAL FEATURES
===

You can write a metacity "plugin" such as a pager, window list, icon
box, task menu, or even things like "window matching" using the
Extended Window Manager Hints. See http://www.freedesktop.org for the
EWMH specification. An easy-to-use library called "libwnck" is
available that uses the EWMH and is specifically designed for writing
WM accessories.

You might be interested in existing accessories such as "Devil's Pie"
by Ross Burton, which add features to Metacity (or other
EWMH-compliant WMs).

METACITY BUGS, NON-FEATURES, AND CAVEATS
===

See bugzilla: http://bugzilla.gnome.org/query.cgi

FAQ
===

Q: Will you add my feature?

A: If it makes sense to turn on unconditionally, or is genuinely a
   harmless preference that I would not be embarrassed to put in a
   simple, uncluttered, user-friendly configuration dialog.

   If the only rationale for your feature is that other window
   managers have it, or that you are personally used to it, or
   something like that, then I will not be impressed. Metacity is
   firmly in the "choose good defaults" camp rather than the "offer 6
   equally broken ways to do it, and let the user pick one" camp.

   This is part of a "no crackrock" policy, despite some exceptions
   I'm mildly embarrassed about. For example, multiple workspaces
   probably constitute crackrock, they confuse most users and really
   are not that useful if you have a decent tasklist and so on. But I
   am too used to them to turn them off.  Or alternatively
   iconification/tasklist is crack, and workspaces/pager are good. But
   having both is certainly a bit wrong.  Sloppy focus is probably
   crackrock too.

   But don't think unlimited crack is OK just because I slipped up a
   little. No slippery slope here.

   Don't let this discourage patches and fixes - I love those. ;-)
   Just be prepared to hear the above objections if your patch adds
   some crack-ridden configuration option.

   http://pobox.com/~hp/free-software-ui.html
   http://pobox.com/~hp/features.html   

Q: Will Metacity be part of GNOME?

A: It is officially part of GNOME as of GNOME 2.2. Prior to that, 
   it was unofficially shipped as the default GNOME WM by several 
   OS vendors.

Q: Is Metacity a Red Hat project?

A: Metacity's original creation was in no way funded, endorsed, or
   encouraged by Red Hat, Inc. - I'm guessing Red Hat would not
   consider "insufficient number of window managers for Linux" an
   urgent problem. Just a wild guess though.

   Now that metacity is the default WM however, Red Hat supports some
   bugfixing and other work.
 
Q: Why does Metacity remember the workspace/position of some apps 
   but not others across logout/login?

A: Metacity only stores sizes/positions for apps that are session
   managed. As far as I can determine, there is no way to attempt to
   remember workspace/position for non-session-aware apps without
   causing a lot of weird effects.

   The reason is that you don't know which non-SM-aware apps were
   launched by the session. When you initially log in, Metacity sees a
   bunch of new windows appear. But it can't distinguish between
   windows that were stored in your session, or windows you just
   launched after logging in. If Metacity tried to guess that a window
   was from the session, it could e.g. end up maximizing a dialog, or
   put a window you just launched on another desktop or in a weird
   place. And in fact I see a lot of bugs like this in window managers
   that try to handle non-session-aware apps.

   However, for session-aware apps, Metacity can tell that the
   application instance is from the session and thus restore it
   reliably, assuming the app properly restores the windows it had 
   open on session save.
   
   So the correct way to fix the situation is to make apps
   session-aware. libSM has come with X for years, it's very
   standardized, it's shared by GNOME and KDE - even twm is
   session-aware. So anyone who won't take a patch to add SM is more
   archaic than twm - and you should flame them. ;-)

   Docs on session management:
    ftp://ftp.x.org/pub/R6.4/xc/doc/hardcopy/SM/xsmp.PS.gz
    ftp://ftp.x.org:21/pub/R6.4/xc/doc/hardcopy/SM/SMlib.PS.gz

   See also the ICCCM section on SM. For GNOME apps, use the
   GnomeClient object. For a simple example of using libSM directly,
   twm/session.c in the twm source code is pretty easy to understand.

Q: How about adding viewports in addition to workspaces?

A: I could conceivably be convinced to use viewports _instead_ of
   workspaces, though currently I'm not thinking that. But I don't
   think it makes any sense to have both; it's just confusing. They
   are functionally equivalent.

   You may think this means that you won't have certain keybindings, 
   or something like that. This is a misconception. The only 
   _fundamental_ difference between viewports and workspaces is that 
   with viewports, windows can "overlap" and appear partially on 
   one and partially on another. All other differences that
   traditionally exist in other window managers are accidental - 
   the features commonly associated with viewports can be implemented
   for workspaces, and vice versa.

   So I don't want to have two kinds of
   workspace/desktop/viewport/whatever, but I'm willing to add
   features traditionally associated with either kind if those
   features make sense.

Q: Why is the panel always on top?

A: Because it's a better user interface, and until we made this not
   configurable a bunch of apps were not getting fixed (the app
   authors were just saying "put your panel on the bottom" instead of
   properly supporting fullscreen mode, and such).

   rationales.txt has the bugzilla URL for some flamefesting on this,
   if you want to go back and relive the glory.
   Read these and the bugzilla stuff before asking/commenting:
     http://pobox.com/~hp/free-software-ui.html
     http://pobox.com/~hp/features.html   

Q: Why is there no edge flipping?

A: This one is also in rationales.txt. Because "ouija board" UI, where
   you just move the mouse around and the computer guesses what you
   mean, has a lot of issues. This includes mouse focus, shade-hover
   mode, edge flipping, autoraise, etc. Metacity has mouse focus and
   autoraise as a compromise, but these features are all confusing for
   many users, and cause problems with accessibility, fitt's law, and
   so on.

   Read these and the bugzilla stuff before asking/commenting:
     http://pobox.com/~hp/free-software-ui.html
     http://pobox.com/~hp/features.html   

Q: Why no wireframe move/resize?

A: Also in rationales.txt. Because it has low usability, and is a pain
   to implement, and there's no reason opaque move/resize should be a
   problem on any setup that can run a modern desktop worth a darn to
   begin with.

   Read these and the bugzilla stuff before asking/commenting:
     http://pobox.com/~hp/free-software-ui.html
     http://pobox.com/~hp/features.html   

Q: Why no XYZ?

A: You are probably getting the idea by now - check rationales.txt,
   query/search bugzilla, and read http://pobox.com/~hp/features.html
   and http://pobox.com/~hp/free-software-ui.html

   Then sit down and answer the question for yourself.  Is the feature
   good? What's the rationale for it? Answer "why" not just "why not."
   Justify in terms of users as a whole, not just users like
   yourself. How else can you solve the same problem? etc. If that
   leads you to a strong opinion, then please, post the rationale for
   discussion to an appropriate bugzilla bug, or to
   usability@gnome.org.

   Please don't just "me too!" on bugzilla bugs, please don't think
   flames will get you anywhere, and please don't repeat rationale
   that's already been offered.

Q: Your dumb web pages you made me read talk about solving problems in
   fundamental ways instead of adding preferences or workarounds.
   What are some examples where metacity has done this?

A: There are quite a few, though many opportunities remain.  Sometimes
   the real fix involves application changes. The metacity approach is
   that it's OK to require apps to change, though there are also
   plenty of workarounds in metacity for battles considered too hard
   to fight.

   Here are some examples:

   - fullscreen mode was introduced to allow position constraints,
     panel-on-top, and other such things to apply to normal windows
     while still allowing video players etc. to "just work"

   - "whether to include minimized windows in Alt+Tab" was solved 
     by putting minimized windows at the *end* of the tab order. 

   - Whether to pop up a feedback display during Alt+Tab was solved by
     having both Alt+Tab and Alt+Esc

   - Whether to have a "kill" feature was solved by automatically
     detecting and offering to kill stuck apps. Better, metacity
     actually does "kill -9" on the process, it doesn't just
     disconnect the process from the X server. You'll appreciate this
     if you ever did a "kill" on Netscape 4, and watched it keep
     eating 100% CPU even though the X server had booted it.

   - The workspaces vs. viewports mess was avoided by adding
     directional navigation and such to workspaces, see discussion
     earlier in this file.

   - Instead of configurable placement algorithms, there's just one 
     that works fairly well most of the time.

   - To avoid excess CPU use during opaque move/resize, we rate limit
     the updates to the application window's size.

   - Instead of configurable "show size of window while resizing,"
     it's only shown for windows where it matters, such as terminals.
     (Only use-case given for all windows is for web designers
     choosing their web browser size, but there are web sites and
     desktop backgrounds that do this for you.)

   - Using startup notification, applications open on the workspace
     where you launched them, not the active workspace when their
     window is opened.

   - and much more.

Q: I think metacity sucks.

A: Feel free to use any WM you like. The reason metacity follows the
   ICCCM and EWMH specifications is that it makes metacity a modular,
   interchangeable part in the desktop. libwnck-based apps such as the
   GNOME window list will work just fine with any EWMH-compliant WM.

Q: Did you spend a lot of time on this?

A: Originally the answer was no. Sadly the answer is now yes.

Q: How can you claim that you are anti-crack, while still 
   writing a window manager?

A: I have no comment on that.