Well, let's try again (MED 6.872):
...
- enter "apply vertices mode";
- click on the hinge point (Yes, i can select it);
- select all vertices of the cube;
- "apply vertices" button IS INACTIVE;

Well, let's try again (MED 6.873):
...
- enter "apply vertices mode";
- click on the hinge point (Yes, i can select it);
- select all vertices of the cube;
- and "apply vertices" is inactive again!

Mistakes may be here coz my English in not perfect.