the current theme jars still contain several images used only in previous version such as

• round corners
• window/panel borders/buttons
• color gradients
• warning error icons
• etc.

e.g.:
https://github.com/zkoss/zk/tree/v8.0.5/zul/src/archive/web/zul/img
https://github.com/zkoss/zk/tree/v8.0.5/zul/src/archive/web/zul/img/button
https://github.com/zkoss/zkThemeTemplate/tree/master/src/archive/web/zul/img/button

(since ZK 7 many of these images were replaced by CSS3 features and font icons)

Unused resources should be removed to reduce jar file size and avoid confusion when creating a custom theme based on the themetemplate project