dreamwinner

This plugin lets you toggle between your native and development language. 
It will help you to find the necessary line in the program code faster. 
Useful when you develop a plugin or perform language debugging. 
This plugin’s button may be found on admin’s dashboard and you can easy switch language anywhere, on any page.
<h3>Note</h3>
You can switch language only if: 
1) you have your native language files .PO and .MO installed in your WordPress CMS 
2) your native language available in your WordPress CMS and your browser can render it

Easy Language Switcher

Switch between English development language and native user language.

ClubDesign

This Plugin replaces the Original WPML Lanuage Switcher in your backend with a brand new one perfectly placed in the Admin Bar! 
It does not touch your frontend language switcher or anything else in your WPML installation.
See the screenshots section, to see the exact changes that will be made.
If you like the new addition, please rate the plugin good. And tell the WPML developers, that we need this implemented in the core of WPML. 😉

Custom WPML Admin Menu (Unofficial Addon)

This Plugin replaces the Original WPML Lanuage Switcher in your backend with a brand new one perfectly placed in the Admin Bar!

Easy Language Switcher vs Custom WPML Admin Menu (Unofficial Addon)