One of the window theme settings does not show its thumbnail.

[kyt]

One of the window theme settings does not show its thumbnail.

steps:
1. select Youker Assitant--> Feature-->ThemeSetting
2.check the "Adwaita" theme.

Ubuntu-14.10-utopic; 32bit ;lenovo

[kobe (kobe24-lixiang)]

Adwaita主题不在系统默认的主题列表中，所以优客助手没有对该主题特意做一个缩略图来显示，目前的做法是凡是在默认主题列表之外的主题，都用那个disappear的图片来表示。

[Sadi Yumuşak (sa-yu)]

I see thumbnails for Ambiance and Radience only, and wonder where they come from.
Perhaps it would be a good idea to use an image file in the theme directory, for example, named "thumbnail.*" if available so that anyone can easily make use of this nice feature.