WMTheme

WMTheme

Print the current window manager theme

Module type	wmtheme
Default order	23 (only used by --gen-config)
Module source	src/modules/wmtheme/wmtheme.c
Detection source	src/detection/wmtheme/

Prints the theme of the window manager that is currently running. The result is one string, not two parts like Modules/Theme.

WM Theme: Breeze
WM Theme: Adwaita
WM Theme: Custom - Blue (System: Dark, Apps: Dark)
WM Theme: Red (Dark)

Platform support

Platform	Implementation	Notes
Linux	wmtheme_linux.c	Per-WM: config files, GSettings / DConf, XFConf, GTK theme as a fallback
Android	wmtheme_linux.c	Same file
FreeBSD / NetBSD / OpenBSD / DragonFly	wmtheme_linux.c	Same file
Solaris / illumos	wmtheme_linux.c	Same file
GNU/Hurd	wmtheme_linux.c	Same file
macOS	wmtheme_apple.c	Accent colour plus the interface style
Windows	wmtheme_windows.c	Theme file name, accent colour and the light/dark preference
Haiku	wmtheme_haiku.cpp	DecorInfoUtility::CurrentDecorator()

Every platform has an implementation.

Configuration

Key	Type	Default	Description
key	string	WM Theme	Module key. A single space hides the key and the separator
keyColor	color	–	Overrides display.color.keys
keyIcon	string	built-in glyph	Printed when display.key.type includes the icon bit. Any glyph works; "" prints none.
keyWidth	integer	–	Overrides display.key.width
outputColor	color	–	Overrides display.color.output
format	string	–	Custom output format (see below)
condition	object	–	Show the module only if the conditions match

There are no module-specific options.

Format string

Run fastfetch -h wmtheme-format for the authoritative list.

Variable	Description
{result}	WM theme

{result} is not marked * in the help output, so it is not available in the key format. It is the only variable the module has — the default output and {result} are the same string.

JSON output

[
    {
        "type": "WMTheme",
        "result": "Custom - Blue (System: Dark, Apps: Dark)"
    }
]

• result is a plain string, not an object and not an array — the whole theme is one value.
• On failure the object carries error instead and has no result.

Examples

// Hide the module unless a theme was found (an error is invisible by default anyway)
{ "type": "wmtheme", "format": "{?result}{result}{?}" }

Pitfalls

• The result is a single string, so nothing is structured. There is no way to ask for "just the accent colour" on Windows or "just the style" on macOS through the format string — the module composes one string and hands it over.
• On Windows the value is not a window-manager theme at all. It is the file name of the active .theme file (with the extension stripped and the first letter capitalised), optionally followed by - <accent name or #RRGGBB>, optionally followed by (System: Light|Dark, Apps: Light|Dark) from Themes\Personalize. Each part is skipped when its registry value is missing, so Custom, Custom - Blue and Custom - Blue (System: Dark, Apps: Dark) are all valid shapes.
• The Windows accent colour is a fixed name table, and a hit is a guess. The registry value is an RGB triple that is looked up in a hard-coded list of about 50 Windows accent colours; a miss falls back to #RRGGBB. The same colour can therefore be named on one machine and printed as hex on another if the list drifts from the installed Windows version.
• Windows reports the light/dark preference for two separate things. SystemUsesLightTheme and AppsUseLightTheme are printed together, because they can disagree; a single "is dark mode on" answer does not exist there.
• WM Theme needs successful WM detection is the first failure mode on Unix. The module starts from ffDetectWM(); without a window manager name it errors out immediately. A TTY session therefore reports this error rather than a theme.
• Only a fixed list of window managers is supported on Unix. kwin (config file, defaulting to Breeze), cosmic-comp, xfwm4 (and labwc under XFCE), mutter (GNOME only — other desktops fall back to the GTK theme), muffin, marco, openbox and enlightenment have branches; anything else reports Unknown WM: <name>. Notably i3, sway, hyprland and bspwm are not in the list.
• The Plasma-specific prefixes are stripped. kwinrc's theme value often carries a qml_ or svg__ prefix that Plasma adds internally; both are removed, and the value after the last prefix wins.
• muffin can return two names in one string. When Cinnamon reports both org.cinnamon.theme::name and org.cinnamon.desktop.wm.preferences::theme, the result is <name> (<theme>); with only one of them set, that one is printed alone.
• COSMIC comp's value is assembled from several files, and includes an accent colour. The variant comes from is_dark, the name from CosmicTheme.<Variant>/v1/name (falling back to Dark / Light), and the accent from a Rust-debug-formatted struct that is parsed for red / green / blue / alpha — printed as #RRGGBB when opaque and #RRGGBBAA otherwise.
• openbox parses XML by hand. The <theme><name> node is located with strstr(), so a <name> that appears after </theme> is rejected, and a missing node yields Couldn't find theme node in "…". The config file is openbox/rc.xml, or openbox/lxqt-rc.xml / openbox/lxde-rc.xml under LXQt / LXDE.
• Errors are invisible by default. Every failure string goes through ffPrintError() and needs display.showErrors to be true.

Implementation

ffDetectWmTheme() takes a single FFstrbuf* that is either the theme or the error message — hence the name themeOrError — and returns a bool. ffPrintWMTheme() prints the buffer on success and passes the same buffer through ffPrintError() on failure; the JSON path writes it to error or result accordingly.

Unix

ffDetectWmTheme() dispatches on the display server's pretty WM name. Four mechanisms are used:

• Config files — kwin (kwinrc, theme =, default Breeze), openbox (rc.xml variants), COSMIC (~/.config/cosmic/…).
• GSettings / DConf — mutter's user-theme extension, muffin (two keys), marco (org.mate.Marco.general::theme).
• XFConf — xfwm4 (/general/theme).
• GTK theme as a fallback — detectGTKThemeAsWMTheme() tries GTK4, then GTK3, then GTK2, and is the whole answer for mutter on a non-GNOME desktop and for enlightenment.

macOS

Two CFPreferencesCopyAppValue() reads against kCFPreferencesAnyApplication — the same values the system exposes through defaults:

• AppleAccentColor maps to a name (-1 Graphite, 0–6 Red / Orange / Yellow / Green / Blue / Purple / Pink, anything else Unknown), and an unset key means Multicolor, which is the default on macOS.
• AppleInterfaceStyle is appended in parentheses; when it is unset the result is (Light), since macOS only stores the key while dark mode is active.

The preferences are read through cfprefsd rather than the raw plist file, so the answer matches what the system itself sees.

Windows

Three registry reads, each optional: Themes::CurrentTheme for the file name, DWM::AccentColor (a BGR value that is byte-swapped to RGB) with DWM::ColorizationColor as the fallback, and Themes\Personalize::SystemUsesLightTheme / AppsUseLightTheme. When nothing at all was found the module reports Failed to find current theme.

Haiku

A BApplication is created — required before the app_server can be queried — and DecorInfoUtility::CurrentDecorator() supplies the name.