Here’s a plugin that lets the themes in the Theme Contest repository work with the Theme Switcher plugin you find in Plugin Manager.
This is really confusing. The WP Plugin Manager refers to a central database of plugins. It has a Theme Switcher Plugin. To use it you add a call to
get_theme_switcher() in sidebar.php where you want the list of themes to appear. If you have Plugin Manager installed, with one click you can install or update Theme Switcher. Then all you need to do is edit every one of the themes you download to put the correct snippet of code in sidebar.php.
The WP Themes contest that I’ve mentioned before refers to a different Theme Switcher plugin. It works pretty much the same way, except it uses a different name for the function to be called from sidebar.php. If you install that Theme Switcher plugin, then all you do is download the themes from the contest site. They all have the correct code in their sidebar.php to work with this Theme Switcher.
Oops. That isn’t the Theme Switcher you get when you update in Plugin Manager.
The solution: Theme Switcher Shim, a plugin that I am submitting to the WP Plugin Manager database.
If you have WP Plugin Manager, you can get it with a one click install. There is no configuration involved in using it. When you have Theme Switcher plugin installed from Plugin Manager, then Theme Switcher Shim will just work. If you don’t have the Theme Switcher plugin installed, the shim detects that and does nothing.
You can install Theme Switcher Shim manually by unzipping theme-switcher-plugin.php into your wp-contents/plugins/ directory, but it doesn’t make a whole lot of sense to do so: Its usefulness is in regards to WP Plugin Manager and the one-click install.