Using Virtualmin, the theme changing interface is confusing.
In order to retain access to virtualmin menus and features, one theme has to be selected in the webmin themes page, and another theme has to be selected in the themes and languages page, thought the list of themes is the same, and it is not obvious that these two theme settings can differ from oneanother, and even less obvious that they in face must be different in order to user Virtualmin correctly.
I think that the wording of these pages could be changed to clarify what they affect, and how they influence webmin / virtualmin respectively. Ideally there would only be one theme configuration page, not two, and the ability to install new themes etc. would be presented there.
Initially I believed that new themes could not be installed on webmin / virtualmin any longer because the themes/languages page offered no facility to do this. It is not obvious that there are more theme configuration options in the webmin theme configuration page which extend the basic options presented on the themes and languages page.
Also I discussed on IRC the meaning of the radio button: Webmin UI theme Global theme (Virtualmin Framed Theme) and again it was not clear what this setting changed.
Generally I think that the user interface for handling themes should be improved and better documented (perhaps with contextual help).
Thanks!
So the way it works is like this - you can change the global theme at Webmin -> Webmin Configuration -> Webmin Themes. This applies to all users who have no chosen a custom theme.
The per-user theme can be set at Webmin -> Change Language and Theme.
If you are using Virtualmin, you pretty much never want to change the theme as the "Virtualmin Framed Theme" is responsible for providing the left menu and many UI elements.