Croma

CAFE Croma is a fork of GNOME Metacity.

COMPILING CROMA

You need CTK+ 3.14. For startup notification to work you need libstartup-notification at http://www.freedesktop.org/software/startup-notification/.

REPORTING BUGS AND SUBMITTING PATCHES

Report new bugs on https://github.com/cafe-desktop/croma. 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 on GitHub. 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; Croma 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 Croma.

SHRINKING CROMA

Not that croma is huge, but a substantial amount of code is in preferences handling, in static strings that aren't essential, and in the theme engine.

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

--disable-sm
--disable-verbose-mode
--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 croma, 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-ctk, which would implement the interface in ui.h without using CTK. This one is easier than you think because the main part of the window manager doesn't use CTK 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 CTK configure script feature to build CTK with only a small core set of functionality.

CROMA FEATURES

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

• Uses CTK+ 3.0 for drawing window frames. This means colors, fonts, etc. come from CTK+ theme.

• Does not expose the concept of "window manager" to the user. Some of the features in the CAFE control panel and other parts of the desktop happen to be implemented in croma, such as changing your window border theme, or changing your window navigation shortcuts, 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 croma extensions, pagers, and so on. (But libwnck isn't croma specific, or CAFE-dependent; it requires only CTK, 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 gsettings:

  gsettings set org.cafe.Croma.general theme Menta
  gsettings set org.cafe.Croma.general theme BlackCAFE
  gsettings set org.cafe.Croma.general theme TraditionalOk
  

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

• Change number of workspaces via gsettings:

  gsettings set org.cafe.Croma.general num-workspaces 5
  

  Can also change workspaces from CAFE 2 pager.

• Change focus mode:

  gsettings set org.cafe.Croma.general focus-mode mouse
  gsettings set org.cafe.Croma.general focus-mode sloppy
  gsettings set org.cafe.Croma.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:

  gsettings set org.cafe.Croma.global-keybindings switch-to-workspace-1 '<Alt>F1'
  

  Also try the CAFE keyboard shortcuts control panel.

  See croma.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 croma.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:

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

• Croma implements much of the EWMH window manager specification from freedesktop.org, as well as the older ICCCM. Please refer to the COMPLIANCE file for information on croma compliance with these standards.

• 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 CDK_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 "croma --replace" to replace it with Croma.

• does basic colormap handling

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

HOW TO ADD EXTERNAL FEATURES

You can write a croma "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 Croma (or other EWMH-compliant WMs).

CROMA BUGS, NON-FEATURES, AND CAVEATS

See github: https://github.com/cafe-desktop/croma/issues

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. Croma 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: Why does Croma remember the workspace/position of some apps but not others across logout/login?

A: Croma 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, Croma 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 Croma 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, Croma 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: http://www.fifi.org/doc/xspecs/xsmp.txt.gz http://www.fifi.org/doc/xspecs/SMlib.txt.gz

See also the ICCCM section on SM. For CAFE apps, use the CafeClient 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. Croma 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 does wireframe move/resize suck?

A: You can turn it on with the reduced_resources setting.

But: 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

The reason we had to add wireframe anyway was broken proprietary apps that can't handle lots of resize events.

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 croma has done this?

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

A: Feel free to use any WM you like. The reason croma follows the ICCCM and EWMH specifications is that it makes croma a modular, interchangeable part in the desktop. libwnck-based apps such as the CAFE 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.