I'm looking for a shortcut or menu command that can collapse all class regions only in one esembly
example:

namespace XX.YY
{
    class A  //collapse

    class B   //collapse

    class C   //collapse

    class D    //collapse

    class E    //collapse
    .....
    ....
    ..

}

After searching i found this shortcut
CTRL M+O it's collapse all methods regions in all assembly file
CTRL M+P collapse all methods regions in all assembly file

there is command CTRL+ M+M
it collapse spesific region only and not helping me

I am looking for shortcut to collapse all class in all assembly file
(i am using vs 2008)

I would generally just right-click, outlining, toggle all outlining and then open up the main one and voila you have classes collasped.

I am using VS2010 but i assume it'll be similar.