GTK

GTK is Article description::a toolkit for creating graphical user interfaces. It is part of the GNU Project and maintained by GNOME.

GTK-2 and GTK-3
For gtk-2 and -3, users can install the libraries with the following command:

Some applications may optionally be built with support for a GTK interface when enabling the  USE flag. Users may even choose to enable GTK support for all packages in.

GTK-4
In Gentoo, Gtk-4 is provided by, a separate package.

Configuration
The following programs can be used to change the appearance of applications using the GTK toolkit:


 * - part of the LXDE desktop environment

Mouse scrolling doesn't work
With the gtk-3 applications under fvwm or other window manager / desktop environments, mouse scrolling sometime doesn't work as it should or at all. At the same time, it work with the applications using other toolkit environments like Qt, which imply this is not a system or Xorg configuration issue. To fix that issue, to add the following environmental variable should work, as example: