                      MOUSE BUTTON USE

    Button 1 alone:

      Item picking.  The items that can
      be picked are individual atoms, bases,
      base pairs and stems. The picking of
      an atom is done from the 3D drawing.
      Otherwise, any item may be picked from
      the 2D or 3D drawing.

      Picking is usually done in response to
      a directive requiring designation of
      a particular item; but an atom or base
      can be picked independently of any such
      directive. When an atom or base is picked,
      its identity is displayed in the lower
      left hand corner of the window from which
      it is picked so long as Button 1 remains
      pressed

      A stem is picked by picking any of
      its displayed complementary bonds
      (the lines connecting its
      complementary bases), and a basepair
      is picked by picking its complementary
      bond.

    Button 1 followed by the Shift key:

      Picking a base (nucleotide) in this manner
      results in the toggling on and off the
      enabling of its display whether or not
      it falls within the group of bases selected
      by the 'NucShowMode' item of the 'Params'
      pulldown. Note, however, that for any base
      to be actually diplayed the 'nucleotide'
      item of the '3D Features' pulldown menu
      must be in the 'on' state.  In the 'off'
      state no bases can be displayed.

    Button 1 followed by the Alt key:

      Picking a nuc marker in this manner results
      in the center of mass of the current level
      to be the backbone atom of the corresponding
      base.

    Button 1 with Button 3:

      Zooming when mouse moves in X direction.

    Button 2 alone:

      Translation in X and Y directions when
      mouse moves in X and Y directions,
      respectively.

    Button 2 with Button 3:

      Rotation about Z-axis when mouse moves
      in X-direction.

    Button 3 alone:

      Rotation about X and Y axes when mouse
      moves in X and Y directions respectively.

                          THE END

