linux/gtk/qt: added guide to uniform look in qt and gtk

wiki/linux/gtk.md

@@ -0,0 +1,46 @@
+# GTK
+
+[GTK](https://gtk.org) is an GUI and widget toolkit.
+
+## Setup
+
+On most linux distributions different GTK versions are installed as a dependency of various
+programs that use graphical user interfaces.
+
+### Configurations
+
+GTK has different versions.
+For GTK3 and GTK4 configurations can be achieved by creating the file `settings.ini` in the folders
+`~/.config/gtk-3.0` and `~/.config/gtk-4.0`.
+An example file that enables dark mode, uses the Adwaita theme and sets the default font to
+sans-serif of size 12 looks something like the following.
+
+```txt 
+[Settings]
+gtk-application-prefer-dark-theme = true
+gtk-icon-theme-name = Adwaita
+gtk-font-name = Sans 12
+```
+
+For GTK2 an older version of config files has to be used.
+The file can be found or created at `~/.config/gtk-2.0/gtkrc-2.0`.
+A similar setup to the previous configuration of GTK3 and GTK4 can be achieved by the following.
+
+```txt 
+gtk-theme-name="AdwaitaDark"
+gtk-font-name="Sans 12"
+```
+
+#### Achieving a System-Wide Uniform Look
+
+[Qt](/wiki/linux/qt.md) is the other big widget toolkit in use.
+An easy way to achieve a uniform look of GTK and Qt is the usage of the Adwaita theme in both
+toolkits.
+This is also described in the
+[official Arch wiki](https://wiki.archlinux.org/title/Uniform_look_for_Qt_and_GTK_applications#Styles_for_both_Qt_and_GTK).
+
+Since it is the default theme on GTK it just has to be set inside as described in the 
+[configuration section](#configuration).
+
+For setting the same theme for Qt refer to the
+[corresponding entry](/wiki/linux/qt.md#achieving-a-system-wide-uniform-look).

wiki/linux/lightdm.md

@@ -8,9 +8,9 @@ It is available for both [X](/wiki/linux/x_window_system.md) and Wayland.
 
 On most linux distributions LightDM can be installed with the `lightdm` package.
 Additionally `lightdm-gtk-greeter` and `xorg-server-xephyr` are recommended.
-This setup will work with [LightDM-GTK-Greeter](#lightdm-gtk-greeter) which is the default 
+This setup will work with [LightDM-GTK-Greeter](#lightdm-gtk-greeter) which is the default greeter. 
-[greeter](#greeters) but others may be chosen.
+If another greeter is to be chosen `lightdm-gtk-greeter` does not have to be installed, but an
-If that is the case `lightdm-gtk-greeter` does not have to be installed, but another one.
+alternative for it.
 For a guide on how to set the greeter navigate to the [greeter section](#greeters).
 This section will also discuss various other greeters like the
 [LightDM-Mini-Greeter](#lightdm-mini-greeter).
@@ -67,6 +67,7 @@ If no `greeter-session` is set the default will fall back to the
 
 The [LightDM-GTK-Greeter](https://github.com/Xubuntu/lightdm-gtk-greeter) is the default greeter 
 for LightDM.
+This is the default [greeter](#greeters) of [GTK](/wiki/linux/gtk.md) but others may be chosen.
 
 ### LightDM-Mini-Greeter
 

wiki/linux/qt.md

@@ -25,3 +25,22 @@ To make this config apply for all Qt applications the following line needs to be
 ```sh
 export QT_QPA_PLATFORMTHEME="qt6ct"
 ```
+
+Afterwards `qt6ct` can be used to enable the dark mode or change other configurations.
+
+#### Achieving a System-Wide Uniform Look
+
+[GTK](/wiki/linux/gtk.md) is the other big widget toolkit in use.
+An easy way to achieve a uniform look of GTK and Qt is the usage of the Adwaita theme in both
+toolkits.
+This is also described in the 
+[official Arch wiki](https://wiki.archlinux.org/title/Uniform_look_for_Qt_and_GTK_applications#Styles_for_both_Qt_and_GTK).
+
+A simple way to achieve this in Qt is the installation of
+[adwaita-qt6](https://github.com/FedoraQt/adwaita-qt) which is also available as an
+[AUR](/wiki/linux/package_manager.md#installing-an-aur-program-with-a-specific-version) package.
+After the installation it can be selected by `qt6ct` as described in the
+[configuration section](#configuration).
+
+For setting the same theme for GTK refer to the
+[corresponding entry](/wiki/linux/gtk.md#achieving-a-system-wide-uniform-look).