Uniform Look for Qt and GTK Applications - ArchWiki

# Uniform Look for Qt and GTK Applications

Related articles

- GTK+
- Qt

Qt and GTK+ based programs both use a different widget toolkit to render the graphical user interface. Each come with different themes, styles and icon sets by default, among other things, so the "look and feel" differ significantly. This article will help you make your Qt and GTK+ applications look similar for a more streamlined and integrated desktop experience.

To get a similar look between the two you will most likely have to modify the following:

- Theme: The custom appearance of an application, widget set, etc. It usually consists of a style, an icon theme and a color theme.
- Style: The graphical layout and look of the widget set.
- Icon Theme: A set of global icons.
- Color Theme: A set of global colors that are used in conjunction with the style.

You can choose various approaches:

- Modify GTK+ and Qt styles separately with the tools listed below for each toolkit and aim for choosing similarly looking themes (style, colors, icons, cursors, fonts).
- Use a special theme engine, which intermediates the modification of the other graphical toolkit to match your main toolkit:
  - if you work in KDE Plasma Desktop 4 environment then a GTK-Qt engine is available, which updates GTK+ configuration files automatically so that GTK+ appearance is similar to the Qt one;
  - similarly if you work in the Trinity desktop environment a GTK-Qt and GTK3-Qt engine is available.
  - if you work in other desktop environments, you can choose the QGtkStyle engine (built in Qt), which forces Qt apps to use your GTK+ 2.x theme.

Should you use also GTK+ 3.x toolkit, follow the GTK+ 3.x wiki article to find out how to make it look similar to GTK+ 2.x themes.

Note: Local theme changes usually do not apply to applications run as root. See GTK+#Configuration_programs.

## Styles for both Qt and GTK+

There are widget style sets available for the purpose of integration, where builds are written and provided for both Qt and GTK+, all major versions included. With these, you can have one look for all applications regardless of the toolkit they had been written with.

### KDE Oxygen

Oxygen is a Qt style that comes by default with KDE Plasma 4. In other environments it can be installed with oxygen-kde4. There are various ways of mimicking its appearance that are described below.

#### oxygen-gtk

oxygen-gtk is a port of the Oxygen Qt Style to GTK+ done by the Oxygen developers. The style has GTK+ 2.x and GTK+ 3.x variants which can be installed with the oxygen-gtk2 or oxygen-gtk3 packages.

Note: Before KDE Plasma 4.10, you needed to create the file `~/.kde4/share/config/gtkrc-2.0`, or do so automatically as described below. This is counter-productive with Plasma 4.10’s oxygen-gtk, and you should delete this file after upgrading to prevent it from messing with your colors. Cleanup-removal of `~/.kde4/share/config/gtkrc` might be necessary, too.

##### Automatic procedure

A few dedicated applications are available in the official repositories that are able to change the GTK+ theme.

You can also install kde-gtk-config. After installation, it can be found in System Settings > Application Appearance > GTK Configuration. It allows you to configure the look and feel for both GTK+ 2.x and GTK+ 3.x applications and is integrated with the KDE add-on installer (Get Hot New Stuff), so you can also download and install other GTK+ themes.

#### Oxygen icons

If you are using Oxygen icons and want a consistent look in GTK+ dialogs, you can install the oxygenrefit2-icon-theme icon theme from AUR and set it as your GTK+ icon theme. To apply the theme you can use `lxappearance` (or a similar program) or set it manually by adding the following line to `~/.kde4/share/config/gtkrc-2.0`:

    gtk-icon-theme-name="OxygenRefit2"

Another version of the Oxygen icon theme for GTK+ applications can be installed with the oxygen-gtk-icons package from AUR.

### QtCurve

QtCurve is a highly popular and configurable set of widget styles for GTK+ 2.x, Qt4, Qt5 and KDE4. QtCurve can be installed with the packages from qtcurve group, available in the official repositories. It has many controls for various options, ranging from the appearance of buttons to the shape of sliders.

To manually change the GTK+ theme to QtCurve, you need to create the file `~/.gtkrc-2.0-kde4` with the following content:

    include "/usr/share/themes/QtCurve/gtk-2.0/gtkrc"
    include "/etc/gtk-2.0/gtkrc"

    style "user-font"
    {
        font_name="Sans Serif"
    }
    widget_class "*" style "user-font"
    gtk-theme-name="QtCurve"

Then you need to create the symbolic link `~/.gtkrc-2.0`:

    ln -s .gtkrc-2.0-kde4 .gtkrc-2.0

If you want also specify a font, you can add (and adapt) the following line to the file:

     gtk-font-name="Sans Serif 9"

### Others

Similar style sets are those that look like each other - written and provided for both Qt and GTK+ - but are not necessarily from the same developers. You may have to do some minor tweaking to make them look the same (e.g. kdestyle-klearlook for Qt4/KDE4 and the Clearlooks GTK+ theme).

## Changing styles in each toolkit

You can use the following methods to change the theme used in each environment.

### Qt5 styles

Qt5 decides the style to use based on what desktop environment is used. If it doesn't recognize the desktop environment, it falls back to a generic style. To force a specific style, you can set the `QT_STYLE_OVERRIDE` environment variable. Specifically, set it to `gtk` if you want to use the gtk theme. Qt5 applications also support the `-style` flag, which you can use to launch a Qt5 application with a specific style.

### Qt4 styles

Qt4 styles can be changed in a similar way:

- Using the KDE System Settings (systemsettings), the settings can be found in Common Appearance and Behavior > Application Appearance > Style > Widget Style
- Using the command-line tool `$ kwriteconfig --file kdeglobals --group General --key widgetStyle [name of style]`.
- Using the Qt Configuration (`qtconfig-qt4`) application, the settings can be found in Appearance > Select GUI Style.

Note that while Qt Configuration allows you to choose the theme, font, etc. for Qt apps, you can modify more settings with KDE4 System Settings (e.g. font antialiasing and hinting). However, you can manually set the antialiasing and hinting in `~/.config/fontconfig/fonts.conf` by following the Font configuration instructions.

### Qt3 styles

Qt3 styles can be changed in the following ways:

- Using the KDE3 Control Center (kcontrol), the settings can be found in Appearance & Themes > Style > Widget Style.
- Using the command-line tool `kde-config --style [name of style]`.
- Using the default Qt Configuration (qt3config) application, the settings can be found in Appearance > Select GUI Style.

This article or section is a candidate for merging with GTK+.

Notes: please use the second argument of the template to provide more detailed indications. (Discuss)

### GTK+3 styles

Some applications and methods are available to change the GTK+ 3.x styles:

- kde-gtk-config — Application that allows you to change style and font of GTK+2 and Gtk+3 applications.

  https://projects.kde.org/kde-gtk-config || kde-gtk-config
  After installation, `kde-gtk-config` can also be found in System Settings > Application Appearance > GTK.

- LXAppearance — Desktop independent GTK+2 and GTK+3 style configuration tool from the LXDE project (it does not require other parts of the LXDE desktop).

  http://wiki.lxde.org/en/LXAppearance || lxappearance

- For manual configuration see the GTK+ page.

### GTK+2 styles

Various applications and methods are available to change the GTK+ 2.x styles: (See GTK+3 section above for more.)

- gtk-kde4 — Application that allows you to change style and font of GTK+2 applications in KDE4.

  http://kde-look.org/content/show.php?content=74689 || gtk-kde4
  After installation, `gtk-kde4` can also be found in System Settings > Lost and Found > GTK style.

- GTK+ Change Theme — Little program that lets you change your GTK+ 2.0 theme (considered a better alternative to switch2).

  http://plasmasturm.org/code/gtk-chtheme/ || gtk-chtheme

- GTK+ Preference Tool — GTK+ theme selector and font switcher.

  http://gtk-win.sourceforge.net/home/index.php/Main/GTKPreferenceTool || gtk2_prefs

- GTK+ Theme Switch — Simple GTK+ theme switcher.

  http://muhri.net/nav.php3?node=gts || gtk-theme-switch2

- For manual configuration see the GTK+ page.

### GTK+1 styles

To change GTK1 styles you can install the gtk-theme-switch package from the AUR.

## Theme engines

A Theme Engine can be thought of as a thin layer API which translates themes (excluding icons) between one or more toolkits. These engines add some extra code in the process and it is arguable that this kind of a solution is not as elegant and optimal as using native styles.

### GTK+-Qt engine

Warning:

- There are rendering issues with some Qt styles.
- There is no support for GTK+ 3.

This engine applies all Qt settings (styles, fonts, but not icons) to GTK+ applications, using style plugins directly. It can be installed with gtk-qt-engine from the AUR.

You can access it from the KDE System Settings under Lost and Found > GTK Styles and Fonts or with `kcmshell4 kde-gtk-config`.

To remove the engine, uninstall the package and delete the following files:

    $ rm ~/.gtkrc2.0-kde
    $ rm ~/.kde4/env/gtk-qt-engine.rc.sh
    $ rm ~/gtk-qt-engine.rc

### QGtkStyle

Warning: Depending on GTK theme, this style may cause rendering issues such as transparent fonts or inconsistent widgets.

This Qt style uses GTK+ to render all components to blend in with GNOME and similar GTK+ based environments. It requires at least GTK+ 2.0 and Qt 4.3, although Qt 4.4 or higher is preferred. Beginning with Qt 4.5, this style is included in Qt.

To enable it with `qtconfig-qt4`, choose GTK+ under Appearance > GUI Style. In KDE4 System Settings, choose GTK+ Style under Application Appearance > Style > Applications.

Alternatively, edit the `~/.config/Trolltech.conf` file:

    ~/.config/Trolltech.conf

    ...
    [Qt]
    style=GTK+
    ...

## Tips and tricks

### KDE file dialogs for GTK+ applications

Warning: Some GTK+ applications may not be compatible with KGtk-wrapper (e.g. Chromium), sometimes the wrapper makes the application crash (e.g. Firefox) and even other applications like KDM (when used with e.g. Thunderbird).

kgtk from the AUR is a wrapper script which uses `LD_PRELOAD` to force KDE file dialogs in GTK+ 2.x apps. Once installed you can run GTK+ 2.x applications with `kgtk-wrapper` in two ways (using Gimp in the examples):

- Calling `kgtk-wrapper` directly and using the GTK+ 2.x binary as an argument:

      $ /usr/bin/kgtk-wrapper gimp

- Modifying the KDE .desktop shortcuts files you can find at `/usr/share/applications/` to prefix the `Exec` statement with kgtk-wrapper.

  e.g. with GIMP, edit the `/usr/share/applications/gimp.desktop` shortcut file and replace `Exec=gimp-2.8 %U` by `Exec=kgtk-wrapper gimp-2.8 %U`.

### Run an application with a specific theme

This article or section is a candidate for merging with GTK+.

Notes: General GTK+ tip (Discuss)

You can use custom styles for specific GTK+ 2.x applications. To run an application with a specific theme use:

    GTK2_RC_FILES=/usr/share/themes/QtCurve/gtk-2.0/gtkrc firefox

This will launch Firefox with the QtCurve theme.

### Using a GTK+ icon theme in Qt apps

If you are not using GNOME, run `gconf-editor`, look under desktop > gnome > interface for the `icon_theme` key and change it to your preference. As you're not using GNOME it's possible that you will have to set `export DESKTOP_SESSION=gnome` somewhere in your `~/.xinitrc` or, if you are using LightDM, in `/etc/environment`.

### Improve subpixel rendering of GTK apps under KDE Plasma

See Font_configuration#LCD_filter.

## Troubleshooting

### gtk-qt-engine does not work with OpenOffice

To make OpenOffice respect the Qt theme chosen with the GTK+-Qt Engine you need to add the following line to `/etc/profile` (as root):

    export SAL_GTK_USE_PIXMAPPAINT=1

Also make sure to select "Use my KDE style in GTK applications" in KDE4 System Settings under Lost and Found > GTK Styles and Fonts.

### Qt applications do not use QGtkStyle

Qt will not apply QGtkStyle correctly if GTK+ is using the GTK+-Qt Engine. Qt determines whether the GTK+-Qt Engine is in use by reading the GTK+ configuration files listed in the environmental variable `GTK2_RC_FILES`. If the environmental variable is not set properly, Qt assumes you are using the engine, sets QGtkStyle to use the style GTK+ style Clearlooks, and outputs an error message:

    QGtkStyle cannot be used together with the GTK_Qt engine.

Another error you may get after launching `qtconfig-qt4` from a shell and selecting the GTK+ style is:

    QGtkStyle was unable to detect the current GTK+ theme.

According to this thread, you may simply have to install libgnomeui to solve this issue. This has the added benefit that you don't need to edit a file every time you change your theme via a graphical tool, like the one provided by xfce.

Users of Openbox and other non-GNOME environments may encounter this problem. To solve this, first add the following to your `.xinitrc` file:

    .xinitrc

    ...
    export GTK2_RC_FILES="$HOME/.gtkrc-2.0"
    ...

Note:

- Make sure to add this line before invoking the window manager.
- You can add multiple paths by separating them with colons.
- Make sure to use `$HOME` instead of `~` as it will not properly expand to the user's home directory.

Then specify the theme you want in the `~/.gtkrc-2.0` file using a dedicated application or manually, by adding:

    .gtkrc-2.0

    ...
    gtk-theme-name="[name of theme]"
    ...

Some tools only insert the following include directive in `~/.gtkrc-2.0`:

    .gtkrc-2.0

    ...
    include "/usr/share/themes/SomeTheme/gtk-2.0/gtkrc"
    ...

which apparently is not recognized by all versions of QGtkStyle. You can hotfix this problem by inserting the `gtk-theme-name` manually in your `~/.gtkrc-2.0` file like above.

Note: Style-changing applications will most probably rewrite the `~/.gtkrc-2.0` file the next time you change themes.

If these steps do not work, install gconf and run this command:

    gconftool-2 --set --type string /desktop/gnome/interface/gtk_theme [name of theme]

If you further want to set the same icon and cursor theme, then you have to specify them, too.

    gconftool-2 --set --type string /desktop/gnome/interface/icon_theme Faenza-Dark

This sets the icon theme to Faenza-Dark located in `/usr/share/icons/Faenza-Dark`. For the cursor theme you first have to set the gconf value.

    gconftool-2 --set --type string /desktop/gnome/peripherals/mouse/cursor_theme Adwaita

Then you will have to create the file `/usr/share/icons/default/index.theme` with the following lines:

    [Icon Theme]
    Inherits=Adwaita

### Themes not working in GTK+ apps

If the style or theme engine you set up is not showing in your GTK applications then it's likely your GTK+ settings files are not being loaded for some reason. You can check where your system expects to find these files by doing the following..

    $ export | grep gtk

Usually the expected files should be `~/.gtkrc` for GTK1 and `~/.gtkrc2.0` or `~/.gtkrc2.0-kde` for GTK+ 2.x.

Newer versions of gtk-qt-engine use `~/.gtkrc2.0-kde` and set the export variable in `~/.kde/env/gtk-qt-engine.rc.sh`. If you recently removed gtk-qt-engine and are trying to set a GTK+ theme then you must also remove `~/.kde/env/gtk-qt-engine.rc.sh` and reboot. Doing this will ensure that GTK+ looks for it's settings in the standard `~/.gtkrc2.0` instead of the `~/.gtkrc2.0-kde` file.

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