Elmord's Magic Valley

Software, lingüística e rock'n'roll. Às vezes em Português, sometimes in English.

Posts com a tag: wm

Switching to the i3 window manager

2020-07-19 16:00 +0100. Tags: comp, unix, wm, emacs, in-english

After almost 3 years using EXWM as my window manager, I decided to give i3 a try. And after two weeks using it, I have to say I'm definitely sticking with it.

I had actually tried i3 years ago, but I had never used a tiling window manager before, and for some reason it didn't click for me at the time. This time, after a long time using EXWM (which I picked up more easily at the time since all the commands were the regular Emacs window/buffer commands I already knew), i3 was quite easy to pick up. So here I am.

Why not EXWM?

EXWM has a lot going for it, mainly from the fact of running in Emacs, and therefore benefitting from the general powers that all things built on Emacs have: it's eminently hackable and customizable (and you can generally see the results of your hacks without even restarting it), and can be integrated in your Emacs workflow in various ways (I gave some examples in my previous EXWM post).

However, it also has some drawbacks. EXWM does not really do much in the way of managing windows: essentially, EXWM just turns all your windows into Emacs buffers, and the window management tasks proper (splitting, deciding which Emacs window will display a new X window, etc.) is the built-in window management Emacs uses for its own windows. Which can of course be customized to death, but is not particularly great for large numbers of windows, in my opinion.

Another problem with EXWM is that if Emacs hangs for any reason (e.g., waiting for TRAMP to open a remote SSH file, or syntax highlighting choking on an overly long line in a JSON file or a Python shell), your whole graphical session freezes, because EXWM does not get an opportunity to react to X events while Emacs is hung doing other stuff. This will happen more or less often depending on the kinds of tasks you do with Emacs. (Also, if you have to kill Emacs for any reason, you kill your entire graphical session, though this can be avoided by starting Emacs like this in your .xsession:

until emacs; do :; done

an idea I wish I had had earlier.)

Finally, EXWM is glitchy. Those glitches don't manifest too often, and it's hard to separate the glitches that come naturally with it from the ones caused by my own hacks, but the fact is that I got tired of the glitchiness and hanging, and also I was lured by i3's tabs support, so I decided to switch.

First steps into i3

The first time you start i3, it presents you with a dialog asking whether you want to use Alt or Win (the 'Windows' key, a.k.a. Super) as the modifier key for i3 shortcuts. I recommend choosing Super here, since it will avoid conflicts with shortcuts from applications. i3 will then generate a config file at ~/.config/i3/config.

The generated config file contains all the default keybindings; there are no extra keybindings other than those listed in this file. This is good because you can peruse the config file to have a general idea of what keybindings exist and how their corresponding commands are expressed. That being said, the i3 User's Guide is quite good as well, and you should at least skim over it to get an idea of i3's abilities.

One peculiar thing about the standard keybindings is the use of Super+j/k/l/; to move to the window to the left, down, up, and right, respectively. That's shifted one key to the right of the traditional h/j/k/l movement commands used by Vim and some other programs. The documentation justifies this as being easier to type without moving away from the home row (and also, Super+h is used to set horizontal window splitting), but I ended up changing this to Super+h/j/k/l simply for the convenience of having bindings similar to what other applications use (and then moving horizontal splitting to Super+b, right beside Super+v for vertical splitting).

Unlike EXWM or some other window managers, the i3 config file is not a full-fledged programming language, so it's not as flexible as those other WMs. However, i3 has a trick up its sleeve: the i3-msg program, which allows sending commands to a running i3. Thanks to i3-msg, you can do tasks that require more of a programming language (e.g., conditional execution) by writing small shell scripts. For example, I have a script called jump-to-terminal.sh, which is just:

#!/bin/bash
i3-msg '[class="terminal"] move container to workspace current, focus' | grep -q true || x-terminal-emulator

i.e., try to find an open terminal window and move it to the current workspace; if the operation does not succeed (because there is no open terminal window), open a new terminal. I can then bind this script to a shortcut in the i3 config file. (I've actually changed script later to not move the window to the current workspace, but it shows how you can string multiple i3 commands together applying to the same window.)

Containers, tabs, and more

i3 uses the concept of containers to organize windows: windows themselves are containers (containing the actual X11 window), but the whole workspace is itself a container that can be split into multiple subcontainers that can be arbitrarily nested. Containers can either use a split layout (windows are tiled horizontally or vertically within the container), or a tabbed layout (i3 shows a tab bar at the top of the container, and each contained window is a tab), or a stacked layout (which is the same as the tabbed layout but the tab titles are placed in separate lines rather than side-by-side). You can switch the layout of the current container with the shortcuts Super+w (tabbed), Super+s (stacked), and Super+e (split, toggling between horizontal and vertical tiling).

(Note that what i3 calls "horizontal split container" is a split container with horizontal tiling orientation, i.e., windows are laid out side-by-side. This can be confusing if you expect "horizontal split" to mean that the splitting line will be horizontal. This is the same terminology that Emacs uses for window splitting, but the opposite of Vim.)

Containers can be arbitrarily nested, and you can have different layouts in each subcontainer. For example, you could have your workspace divided into two horizontally-tiled containers, and have a tabbed layout in one of the subcontainers. Note that because of this, it's important to know which container you have selected when you use the layout-changing commands. The colors of the borders tell you that, but it takes a while to get used to paying attention to it. i3 comes with a pre-defined binding Super+a to select the parent of the current container, but not one to select a child; I have found it useful to bind Super+z to focus child for this purpose.

Unnesting containers

The commands Super+v and Super+h (Super+b in my modified keymap) select a tiling orientation for new windows opened in the current container. (Again, the border colors tell you which mode is active.) It implicitly turns the current container into a nested container, so that new windows will become siblings of the current window. It is very easy to create nested containers by accident in this way, especially when you are just starting with i3. Those show up like i3: H[emacs] in the window title (i.e., a horizontally-tiled container containing just an emacs window), and you can even get into multiple levels of nested containers with a single window inside. In these situations, it is useful to have a command to move the current window back to its parent container. Surprisingly, i3 does not have a built-in command for that, but it is possible to concoct one from existing commands (based on this StackExchange answer):

# Move container to parent
bindsym $mod+Shift+a mark subwindow; focus parent; focus parent; mark parent; [con_mark="subwindow"] focus; move window to mark parent; [con_mark="subwindow"] focus; unmark

What this does is to use i3 marks (which are like Vim marks, allowing you to assign labels to windows) to mark the current window and its parent's parent, and then moving the window to inside its parent's parent (i.e., it becomes a sibling of its current parent).

The status bar

In EXWM, I had recently implemented a hack to display desktop notifications in the Emacs echo area. I hate desktop notifications appearing on the top of what I'm doing (especially when I'm coding), and I had most of them disabled for this reason until recently, but Slack notifications are useful to see at work. With this hack, I could finally have non-obtrusive desktop notifications. I was only going to switch to i3 if I could find a way to have similar functionality in it.

i3 does not exactly have an echo line, but it does have a desktop bar which shows your workspaces to the left, tray icons to the right, and the output of a status command in the middle. The status command can be any command you want, and the status line shows the last line of output the command has printed so far, so the command can keep updating it. i3bar actually supports two output formats: a plain-text one in which every line is displayed as-is in the status line, and a JSON-based format which allows specifying colors, separators and other features in the output.

This means that you can write a script to listen for D-Bus desktop notifications and print them as they come, together with whatever else you want in the status line (such as a clock and battery status), and blanking them after a while, or when a 'close notification' message is received. I have done just that, and it works like a charm. (It requires python3-pydbus to be installed.) The only problem with this is that the content of the status line is aligned to the right (because it is meant to be used for a clock and stuff like that), and there is no way to make it aligned to the left, so I actually pad the message to be shown with spaces to a length that happens to fit my monitor. It is sub-optimal, but it works well enough.

Conclusion

I'm pretty happy with the switch to i3. Although I've lost the deep integration with Emacs, it has actually been an improvement even for my Emacs usage, since i3 tabs supplement Emacs's lack of tabs better than any tabbing package I have seen for Emacs. (Having tabs for all programs, including things like Evince, is really nice.) If you are interested in tiling window managers and are willing to spend a few days getting used to it, I definitely recommend it.

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Making new Pidgin conversation windows not appear on top of other windows in Xfce

2016-02-14 17:05 -0200. Tags: comp, unix, wm, in-english

Recently I started using Xfce/Xfwm instead of IceWM. One of the problems I had after migrating is that Xfwm places new Pidgin conversation windows on the top of existing windows, obstructing whatever I am doing. At least it doesn't give focus to the new window, but ideally the window should be placed in background.

The solution I found was, well, modifying the source code. Fortunately, there is only a single line to be changed.

  1. Download Xfwm 4.12's source code, unpack it (tar -xvf xfwm4-4.12.0.tar.bz2) in a place of your choosing, and enter the xfwm4-4.12.0 directory.

  2. In the file src/focus.c, replace line 232, which says:

                clientRaise (c, None);

    with:

                clientLower (c, None);
  3. Run ./configure. If it complains about missing libraries, you will have to install the corresponding development (header) packages from your distribution. On Debian, Ubuntu and similar, these packages have names ending in -dev. For instance, if ./configure complains that libxfce4ui-1 is missing, you will have to install the package libxfce4ui-1-dev.

    Update: You can install all(?) dependencies with:

    sudo apt-get install intltool libx11-dev libgtk2.0-dev libxfce4util-dev libxfce4ui-1-dev libwnck-dev 
    
  4. After ./configure succeeds, run make, then make install.

  5. If everything succeeded, test the newly compiled window manager by running xfwm4 --replace. (You may have to specify the full path, e.g., /usr/local/bin/xfwm4 --replace, to make sure you are using the newly compiled Xfwm, not the one that came with your distro.) If the new window manager works, you are done! (If anything goes wrong, you can run make uninstall to undo the installation, then run /usr/bin/xfwm4 --replace to re-run the original Xfwm.)

One day, maybe, I may try to turn this into a configuration option in Xfwm and submit a patch. One day...

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