Mend Themes

Applications native to one desktop environment can look out of place when run on another. For example, a GNOME app running on KDE Plasma may have a different title bar, button style, and icon style; similarly for a KDE Plasma app run on GNOME.

To unify their look, desktop environments tweak themes to have non-native applications blend in better. They may not revert those tweaks on log out, however, leaving you with a mess when you then log in to a different desktop environment.

GNOME before using KDE Plasma: the icons and cursor follow the default Adwaita theme.

GNOME after using KDE Plasma: the cursor is large and poorly rendered, the icons and cursors now follow the Breeze theme (default for KDE Plasma).

To have Mending Wall fix all this, enable the Mend Themes feature. It ensures that the theme chosen for each desktop environment is maintained across sessions, even when running other desktop environments in between.

What it does

Mend Themes saves the theme during each desktop session, then restores it when you next log in to the same desktop environment. For example:

1. While you are running GNOME, Mending Wall saves the theme.
2. If you log out of GNOME and into KDE Plasma, KDE will make some changes to the GNOME theme to improve the user experience on KDE. Mending Wall will save the theme for KDE too.
3. If you then log out of KDE and back into GNOME, Mending Wall will restore the GNOME theme that it previously saved, so that KDE's changes do not interfere with GNOME. GNOME may also make some tweaks to the KDE theme at this stage.
4. Similarly, when you log back into KDE in future, Mending Wall will restore the KDE theme that it previously saved, so that GNOME's tweaks do not interfere with KDE either.

How it works

Info

This section is for users who want to know exactly what Mending Wall is doing to their system.

When Mend Themes is enabled, Mending Wall starts a background process named mendingwalld that will also auto-start every time you log in. The process starts in one of two modes:

1. Save to make a copy of the theme, monitor for changes, and update the save. This mode is used when Mend Themes is enabled for the first time (or re-enabled after being disabled).
2. Restore to restore the previous save, monitor for changes, and update it. This is used for the auto-start every time you log in.

A save includes:

1. Any number of GSettings paths. These are typically used for configuration by desktop environments based on GTK, such as GNOME and Cinnamon. The save is kept as a keyfile at $XDG_CONFIG_HOME/mendingwall/save/$XDG_CURRENT_DESKTOP.gsettings, where groups identify the GSettings paths and keys the GSettings keys.
2. Any number of config files under $XDG_CONFIG_HOME/. Such config files may be used by any desktop environments, including those based on GTK, but also Qt, such as KDE Plasma, or other toolkits. Saved files are kept under $XDG_CONFIG_HOME/mendingwall/save/$XDG_CURRENT_DESKTOP/.

XDG_CURRENT_DESKTOP is an environment variable set by the desktop environment. XDG_CONFIG_HOME is an environment variable that may or may not be set by the desktop environment; if not set, the default value of $HOME/.config is used.

Configuration

Info

This section is for contributors to help improve Mending Wall. The installed configuration is meant to be suitable for everyone with no adjustments required, rather than something that is routinely modified.

The specific GSettings paths and config files to back up and restore are set in the config file themes.conf. If the environment variable XDG_CONFIG_HOME is set and $XDG_CONFIG_HOME/mendingwall/themes.conf exists then that file is used, otherwise $HOME/.config/mendingwall/themes.conf, otherwise the directories listed in XDG_CONFIG_DIRS are checked in order for mendingwall/themes.conf until the file is found.

If themes.conf is in a system directory and you wish to make changes to it, first copy it to $XDG_CONFIG_HOME/mendingwall/themes.conf or $HOME/.config/mendingwall/themes.conf.

The config file is a KeyFile. It contains any number of group headers to identify desktop environments, each followed by key-value pairs that specify the GSettings paths and config files to backup and restore. For example:

[GNOME]
GSettings=org.gnome.desktop.interface

[KDE]
ConfigFiles=kwinrc;kcminputrc

The group headers are surrounded by square brackets ([...]) and identify the desktop environments. The environment variable XDG_CURRENT_DESKTOP is used to determine which group to use. If XDG_CURRENT_DESKTOP lists multiple desktop environments (e.g. Budgie:GNOME, note colon-separated in this case, as per the specification) then it is treated as if one value; in this context such combinations really indicate a distinct desktop environment (e.g. Budgie:GNOME really just indicates Budgie).

Each key is followed by an equals sign (=), and where multiple values are required they are separated by semicolons (;). Recognized keys are:

Key	Value
GSettings	GSettings schemas to save and restore.
ConfigFiles	Config files to save and restore. Each should be relative to the $XDG_CONFIG_HOME/ (or default $HOME/.config/) directory. There is no support for directories or recursion.

Tip

You may notice that the current themes.conf has the same GSettings and ConfigFiles for all desktop environments. If the pattern continues, the config file may be simplified in future, but for now it allows different configuration for different desktop environments, in case that becomes useful.

Related specifications

• The XDG Base Directory Specification for the XDG_CONFIG_HOME environment variable.
• The Recognized desktop entry keys section of the XDG Desktop Entry Specification for the XDG_CURRENT_DESKTOP environment variable.