Thread:Project:Support desk/Collapsible navigation not work - MW 1.20

Hello everyone, having the issue, that parts of my left navbar isn't work correctly. Is there a possible solution, a guide or any other useful stuff, to fix this bug? Tested with following browser: Firefox 17.0.1, Google Chrome 23.0.1271.97 m, Rockmelt 0.16.91.483, Opera 12 and IE 9.0.8112.16421 (only working with Rockmelt (only shows the toolbox). Any help is appreciated. Thank you in advance. Sandro