Good or Bad C++ Idiom - Objects used purely for constructor/destructor?

I have a few classes which do nothing except in their constructors/destructors. Here's an example

class BusyCursor 
{
  private:
    Cursor oldCursor_;

  public:

    BusyCursor()
    {
      oldCursor_ = CurrentCursor();
      SetCursor(BUSY_CURSOR);
    }
    ~BusyCursor()
    {
      SetCursor(oldCursor_);
    }
}

// example of use
    void DoSlowThing
    {
      BusyCursor busy;
      ... do something time-consuming  ...
    }

I'm a little concerned about future readability. Am I being too "tricksy" here, with a variable ("busy") which is never actually used in the code? Could some static analysis tool suggest they be removed, or is this idiom sufficiently common not to worry about?