i3-MultiMonitor-Workspace

⚠️ This software is a Minimum Viable Product.

Been using it for a while on my own setup. There might be some problems, feel free to fill up an issue

The problem

When using i3 windows manager, each monitor get assigned an individual workspace. I find it easier to separate tasks/concerns with a virtual workspace spanning across all monitors. I googled for a while but couldn't find a satisfying solution.

Solution

i3-multimonitor-workspace is a python daemon that listen to workspace changes and reflect the changes across all monitors using i3ipc commands.

How does it work

Let's say we have a 3 monitor setup (HDMI-1, DVI-1, DP-1) with 3 global workspaces. The following workspaces will be spawned by the daemon :

DVI-1
	1:1
	2:2
	3:3
HDMI-1
	11:1
	12:2
	13:3
DP-1
	21:1
	22:2
	23:3

For example, when the user navigate to the workspace 2 using modKey+2, the daemon will bring up the workspaces 2,12 and 22 thus creating the effect of a Multi Monitor Workspace. Since the daemon is listening to WORKSPACE_FOCUS events, there is no need to change keybindings (except for specific cases, see i3 Configuration).

The biggest challenge is to keep all the individual workspaces opened even when there is no spawned window inside it. i3 is built to clear a workspace when it's empty unfocused. To workaround this, we spawn dummy windows that are used as placeholders (This first version uses terminal windows as placeholders which is definitely not the most efficient solution, see Known Issues for more details). These placeholders are moved to the scratchpad when the multimonitor workspace is focused and moved back to the individual workspaces when it loose focus.

Setup

The following python package is required :

pip install i3ipc

We also make use of these linux packages :

xdotool
dmenu
wmctrl

Simply cloning this repository and running python3 i3-multimonitor-workspace.py will start the daemon. We recommend launching it inside your i3 config

Required i3 configuration

In the future, I hope to find a way to reduce the amount of configuration needed for the daemon to work. In the meantime, here is what you need to add to your configuration (typically in ~/.config/i3/config)

First, the daemon should be started when i3 is launched :

exec_always --no-startup-id "python3 /opt/i3-multimonitor-workspace/i3-multimonitor-workspace.py"

Then, the placeholder windows should be moved to scratchpad automatically :

for_window [instance="empty_workspace"] move to scratchpad

We use an ugly hack to ensure that the placeholders are transparent... We won't need this when we stop using terminal windows as placeholders. This step is optional but without it, you might see some flashes when changing workspace.

Add the following lines to your .bashrc :

if [[ ! -z ${DISPLAY} ]]; then
    EMPTY_PLACEHOLDER_WINDOW_ID=$(wmctrl -lpx | grep "$PPID.*empty_workspace" | awk '{print $1}')
    if [[ ! -z ${EMPTY_PLACEHOLDER_WINDOW_ID} ]];then
        transset --id ${EMPTY_PLACEHOLDER_WINDOW_ID} 0
    fi
fi

Specifying the strip_workspace_numbers option in the i3bar configuration will allow for a more uniform workspace naming :

bar {
	...
    strip_workspace_numbers yes
    status_command i3status
    position top
    tray_output primary
    ...
}

Finally, the workspaces must be assigned to each monitors :

workspace 0 output DVI-1
workspace 10 output HDMI-1
workspace 20 output DP-1

workspace 1 output DVI-1
workspace 11 output HDMI-1
workspace 21 output DP-1

workspace 2 output DVI-1
workspace 12 output HDMI-1
workspace 22 output DP-1

...

workspace 8 output DVI-1
workspace 18 output HDMI-1
workspace 28 output DP-1

workspace 9 output DVI-1
workspace 19 output HDMI-1
workspace 29 output DP-1

Optional i3 configuration

To enable workspace renaming (this keybinding will allow you to set a name to the current multimonitor workspace):

bindsym $superKey+$altKey+r exec "python3 /opt/i3-multimonitor-workspace/i3-multimonitor-workspace.py --rename"

To enable back-and-forth between 2 multimonitor workspace (Similar to Alt+Tab) :

bindsym $altKey+Tab exec "python3 /opt/i3-multimonitor-workspace/i3-multimonitor-workspace.py --back_and_forth"

When moving a window to a specific workspace with the default keybindings (modKey+Shift+3), the window will always be placed on the main monitor. The --move_to_workspace parameter can be used to move the window to another multimonitor workspace while keeping the window on the same monitor. Use this configuration to enable this feature :

bindsym $altKey+Shift+0 exec --no-startup-id "python3 /opt/i3-multimonitor-workspace/i3-multimonitor-workspace.py --move_to_workspace 0"
bindsym $altKey+Shift+1 exec --no-startup-id "python3 /opt/i3-multimonitor-workspace/i3-multimonitor-workspace.py --move_to_workspace 1"
bindsym $altKey+Shift+2 exec --no-startup-id "python3 /opt/i3-multimonitor-workspace/i3-multimonitor-workspace.py --move_to_workspace 2"
bindsym $altKey+Shift+3 exec --no-startup-id "python3 /opt/i3-multimonitor-workspace/i3-multimonitor-workspace.py --move_to_workspace 3"
bindsym $altKey+Shift+4 exec --no-startup-id "python3 /opt/i3-multimonitor-workspace/i3-multimonitor-workspace.py --move_to_workspace 4"
bindsym $altKey+Shift+5 exec --no-startup-id "python3 /opt/i3-multimonitor-workspace/i3-multimonitor-workspace.py --move_to_workspace 5"
bindsym $altKey+Shift+6 exec --no-startup-id "python3 /opt/i3-multimonitor-workspace/i3-multimonitor-workspace.py --move_to_workspace 6"
bindsym $altKey+Shift+7 exec --no-startup-id "python3 /opt/i3-multimonitor-workspace/i3-multimonitor-workspace.py --move_to_workspace 7"
bindsym $altKey+Shift+8 exec --no-startup-id "python3 /opt/i3-multimonitor-workspace/i3-multimonitor-workspace.py --move_to_workspace 8"
bindsym $altKey+Shift+9 exec --no-startup-id "python3 /opt/i3-multimonitor-workspace/i3-multimonitor-workspace.py --move_to_workspace 9"

Tradeoff

At first, I wanted this software to be as transparent as possible which is why I am listening to WORKSPACE_FOCUS events. This however doesn't give the best user experience. The workspace identifiers might flash when changing the multimonitor workspace because the individual workspace get removed and recreated quickly. This is a limitation of being event based (When we receive the WORKSPACE_FOCUS event, the previous workspace has already lost it's focus so it already got removed by i3). One way to workaround this would be to do all workspace changes via keybindings (replacing all the default one with specific one). I might explore this later.

Limitations/Known issues

• Doesn't support plugging/unplugging of monitors. The daemon must be restarted and the config must be modified according to the new monitor setup (the workspace monitor assignement config)
• The number of multimonitor workspaces is limited to 10 (10 * NbMonitor individual workspaces).
• The daemon will only start when more than 1 monitor is connected (loosing the --back_and_forth and --rename capabilities)
• --back_and_forth can be a bit slow
• When fast switching between multimonitor workspace, an individual workspace might get "deleted" causing some jittering in the menu bar. Focusing back on this multimonitor workspace should sync back the individual workspaces.
• When moving a container to a new workspace (Alt+Shift+7 when workspace 7 doesn't exist), Only the workspace on the main monitor will be created. Not a big issue, when focusing the newly created workspace the other workspaces will be created.
• Sometime when a window is in fullscreen and we switch workspace, the container is not fullscreen anymore when we get back to the workspace.
• When changing workspaces too quickly (By pressing down a binding for "Next workspace" and not releasing it for a couple of seconds), the multimonitor workspace changes won't be handled (for performance reasons). Switching back to the affected workspaces should sync them back.
• Depending on your computer load (Ram almost full, CPU 100%, etc..), it might take some time for the focus events to be propagated which feel kinda laggy.
• Changing workspace via mouse click in the status bar might cause the wrong monitor to be focused after the workspace change.
• If you connect a second monitor while some workspaces already exist and attempt to relaunch the manager, everything will go to hell :) The best course of action here is to close all workspaces before relaunching the workspace manager.

TODO :

• Publish a package on pip
• More testing with different monitor configurations
• Script that auto generate the necessary i3 config
• Add possibility to specify default workspaces (Will be automatically created/renamed on launch)
• The daemon keep the workspace names and the last focused workspace in memory, should write to file instead.
• Fix issues in Limitations/Known Issues
• Refactor: Create a class that wrap the i3 connection instead of adding stuff inside the i3 connection object
• Read/write config from file instead of relying on daemon inmemory config (i3.workspace_names, i3.spawned_placeholders, i3.current_global_workspace_id, i3.last_global_workspace_id)
  • Might lead to race conditions if not careful, need to have some locking mecanism. Simply use lock files ?

Version infos

Tested on Ubuntu 18.04 with Python 3.6.9 and a 3 monitor setup
i3 version 4.16.1-175-gac795ae3 (2019-05-03, branch "gaps-next") 
© 2009 Michael Stapelberg and contributors

I know this is an old version of i3, will test with a newer version when I have some time.

Contributing

Pull requests are welcome !