T3 with permanent Sub-Menus on sidebars?

Hey There,

i want to use standard permanent submenus on the sidebars. They should always be there and be arranged like the standard Joomla submenus. Until now i tried to set the class dopdown-menu to "dispay:block" via a "custom.css". But then all other Menus stay open too.

Is it possible to add a new class into the html code at the right position via Megamenu oder does this only work in the top menu?

Regards