mosheeshel

This plugin extends Theme Switcher and Theme Switcher Reloaded, this plugin detects the existing active plugin and uses it to display a floating list of available themes, to enable creating a Theme demo site.
Basically it enables anyone to create a demo site of all his available themes, just create a site with all the demo pages you can think of. The download and Enable either Theme Switcher or Theme Switcher Reloaded plugins, and this plugin, and when you access any page on the site a floating div will appear on the top left side of the site, showing a dropdown menu wutg the current theme selected. When you choose a different theme from the list, the site will switch to have that theme as the selected site theme.
Note: that this plugin is dependant on either the Theme Switcher or the Theme Switcher Reloaded plugins, and what it does would not be possible without the work done on those plugins.

Floating Theme List

This plugin extends Theme Switcher (/Reloaded), it displays a floating list of available themes, enabling EASY creation of a theme demo site.

Masahiro NAKASHIMA

The theme can be changed and displayed to only logged in users.
The visitors of the website see your old theme while you are testing the new one.
Only the administrator of the WordPress site sees the new theme that can now be tested safely.
You can also use this plugin instead of “Theme Test Drive” plugin.

WP Theme Test

I have xdebug installed. There are two big Notices.

Threw two big PHP notices

The theme can be changed and displayed to only logged in users.

Floating Theme List vs WP Theme Test