FVWMMFL(1)

🎀 FVWMMFL(1) 🎀

Okay bestie, this is the manual page for FvwmMFL, filed under the Fvwm Modules section 🌸

✨ NAME ✨

FvwmMFL, the Fvwm3 front-loader module 💖

💅 SYNOPSIS 💅

FvwmMFL can only be invoked by Fvwm3. Command line invocation of the FvwmMFL will not work. 🙈

This module has no command-line options, so don't even try 💀

🧚 DESCRIPTION 🧚

Okay so the FvwmMFL module gives you access to Fvwm events over a unix-domain socket 🦋 It's basically made for externally-written programs (aka clients) that want to receive info from Fvwm and then do something about that event. Iconic behaviour, honestly 👑

The info Fvwm3 sends is in the form of JSON packets 💜 Each packet has different fields depending on which type was requested, so it's lowkey a whole vibe.

🌸 COMMUNICATION 🌸

The default unix-domain socket for FvwmMFL is $TMPDIR/fvwmmfl/fvwm_mfl_$DISPLAY.sock ✨

Want it somewhere else? Set the FVWMMFL_SOCKET_PATH environment variable to change where fvwm_mfl_$DISPLAY.sock gets created 🧚 FvwmMFL will make that path if it doesn't exist yet, and it'll set the relevant permissions for you. Main character energy 💅

🔥 REGISTERING INTEREST 🔥

Clients can send commands to FvwmMFL to decide which info gets sent to them. The set command handles this 🎀 Here's every event you can subscribe to, bestie:

• new_window — fires when a new window is mapped and visible 🪟
• map — fires when a window is mapped 🗺️
• configure_window — fires when a window is moved or resized 📐
• destroy_window — fires when a window is closed 💀
• new_page — fires when a new page is switched to 📄
• new_desk — fires when a new desk is switched to 🖥️
• raise_window — fires when a window is raised (or changes layer) 🦋
• lower_window — fires when a window is lowered (or changes layer) 🌙
• focus_change — fires when a window loses or gains focus 🎯
• enter_window — fires when the pointer moves into a window 👀
• leave_Window — fires when the pointer moves out of a window 🚪
• window_shade — fires when a window is shaded 🌫️
• window_unshade — fires when a window is unshaded ☀️
• window_name — fires when the window name changes 🏷️
• visible_name — fires when the visible window name changes 👁️
• res_class — fires when the class of the window is set 🧁
• res_name — fires when the resource of the window is set 🎀
• iconify — fires when a window is iconified 🫧
• deiconify — fires when a window is deiconified 🌟
• icon_name — fires when the icon name changes 💫
• visible_icon_name — fires when the icon's visible name changes 🍓
• icon_file — fires when the path to the icon changes 📁
• icon_location — fires when the icon location changes 📍
• restack — fires when the window stacking order changes 🥞
• echo — fires when Fvwm receives an Echo command 📣

For example, to register interest in new_window and focus_change, you'd send these commands over the socket:

set new_window
set focus_change

Changed your mind? Use the unset command to remove interest in an event:

unset focus_change

📦 JSON FORMAT 📦

Each packet sent to a client is plain JSON 🫶 What's inside each packet depends on the event, so keep that in mind.

TODO: document each JSON structure. (Still on the list, bestie 🙈)

🍓 EXAMPLE 🍓

Want to watch focus_change events from the shell and see the JSON that comes back? Slay:

echo set focus_change | nc -U /tmp/fvwm_mfl.sock 2>&1 | jq --unbuffered

It outputs something like this:

{ "focus_change": { "window": "0x5400022", "type": 0, "hilight": {
"text_colour": 16777215, "bg_colour": 32767 } } }

👑 AUTHORS 👑

This module first appeared in 2020 🌈

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That's a wrap, bestie 🦋 FVWMMFL(1), from the Fvwm Modules pages, dated 2026-06-28. Love you, mean it 💖✨