On actual MW and Thanks master git branch if i click on "thanks" (Confirmation is enabled) i become a simple grey overlay and the error in console:
Uncaught TypeError: Cannot read property 'msie' of undefined
This may be because of upgrade from jQuery 1.8 to 1.11.x (see http://firstname.lastname@example.org/msg75735.html), $.browser was deprecated and removed since version 1.9 (see http://api.jquery.com/jQuery.browser/)
So, the thanks function doesn't work for me in actual master versions (maybe other extensions/functions are broken too).
Information about wiki installation:
MW: 1.24alpha (c812315) 21:47, 8 June 2014
PHP: 5.5.3-1ubuntu2.3 (apache2handler)