Since I prefer KDE for my desktop management, GTK application theme looks so ugly, it shows “grey” on Slackware Linux 13.0. I feels like back to 11 years ago :D. Whereas if I use Xfce, GTK application looks normal. So what’s the problem? Here we go, GTK application will read local configuration located on ~/.gtkrc or ~/.gtkrc-2.0 (for GTK2 application). So simply edit or make your config one. vim ~/.gtkrc-2.0 and add this line