Control which GTK theme a specific application uses on Linux.

This post will show you how to open a certain GTK application, like Gedit or Firefox, and force it to use a certain GTK theme.

This example uses the Gedit editor. I am opening the editor using the BlackMATE theme.

jason@Yog-Sothoth » ~ » $ env GTK_THEME="BlackMATE" /usr/bin/pluma
 
(pluma:5423): Gtk-WARNING **: 09:42:13.729: Could not load a pixbuf from icon theme.
This may indicate that pixbuf loaders or the mime database could not be found.

Another example, using the Ambiant-MATE-Dark theme.

jason@Yog-Sothoth » ~ » $ env GTK_THEME="Ambiant-MATE-Dark" /usr/bin/pluma
 
(pluma:6730): Gtk-WARNING **: 09:52:13.019: Could not load a pixbuf from icon theme.
This may indicate that pixbuf loaders or the mime database could not be found.

This goes to show that the theme may be changed on a per-application basis, this would be good if the user wanted a dark theme for a browser, but a normal theme for everything else.

Another good GTK tip. Make the Gnome Shell titlebars much thinner.

http://securitronlinux.com/bejiitaswrath/how-to-make-the-title-bars-in-gnome-shell-much-thinner-than-the-default/.

These tips should be very helpful to a Gnome Shell user that wants thinner title bars and/or a custom GTK theme for a customized desktop environment.