Moving beyond GTK+ themes

[…] the level of visual customisation that is being done at the [Linux] distribution level has led to widespread visual fragmentation which impacts both user- and developer-friendliness. […] user interfaces of the past were much simpler, there were fewer window states, fewer points of interaction, less visual feedback, and just plain fewer pixels. These limitations in old toolkits meant that they largely stayed the same from theme to theme and things were relatively stable.