Changes

If the changes involve modifying the graphics, then other methods may need to be modified as well.  For instance, in order to introduce a reset button that can be clicked to reset the bead positions to the beginning, the following methods had to be modified -- all in abacus_window.py:

If the changes involve modifying the graphics, then other methods may need to be modified as well.  For instance, in order to introduce a reset button that can be clicked to reset the bead positions to the beginning, the following methods had to be modified -- all in abacus_window.py:

# in the <code>class Abacus</code>, methods <code>_button_press_cb()</code> to activate reset button;

# in the <code>class Abacus</code>, method <code>_button_press_cb()</code> to activate reset button;

# in the <code>class AbacusGeneric</code>, method <code>create()</code> to create the graphics for reset button;

# in the <code>class AbacusGeneric</code>, method <code>create()</code> to create the graphics for reset button;

# methods <code>hide()</code> and <code>show()</code> to make the button visible.

# methods <code>hide()</code> and <code>show()</code> to make the button visible.