Plugin could not be activated because it triggered a fatal error.

Seems like the problem is that I have PHP 5.2.5 installed and array_map is supported in PHP >= 4. Any way this plugin could be made compatible with older PHP version?

The problem is for anonymous functions, anonymous functions become available of php >= 5.3.0.

Anonymous functions
https://www.php.net/manual/en/functions.anonymous.php

So, the menubar-widgets plugin doesn’t support your server php version.

Now there is one new fork for the ‘menubar-widgets’ plugins in github for those who use php < 5.3.0.

Please you see this issue on the bitbucket.