code: public ActionMode onLongClick(AppCompatActivity act, int position) {
          if (mActionMode == null && mFastAdapter.getItem(position).isSelectable()) {
              //may check if actionMode is already displayed
              mActionMode = act.startSupportActionMode(mInternalCallback);
              //we have to select this on our own as we will consume the event
              mSelectExtension.select(position);
              // update title
              checkActionMode(act, 1);
              //we consume this event so the normal onClick isn't called anymore
              return mActionMode;
          }
          return mActionMode;
      }
docs: implements the basic behavior of a CAB and multi select behavior onLongClick
  
  @param act      the current Activity
  @param position the position of the clicked item
  @return the initialized ActionMode or null if nothing was done