This window contains the expression that you are currently working on.

Parts of the expression that have been selected are shown in white, other
parts are in black.

To select a part of the expression click on it with the mouse.

* To select an individual variable or constant  (eg "a" or "1") click on the
  symbol itself.

* To select several terms multiplied together click on the space between them
  or click on one then on the Up Arrow Button.
  
* To select the contents of a bracket click on the bracket

* To select terms joined by an operator click on the operator ( eg to select
  "a+b" click on the "+"