The Greek toolbox lets you easily insert Greek letters into your expressions and constraints.
To insert Greek letters into a variable name or expression, select the appropriate button from the Uppercase (Greek Capital) or Lowercase (Greek Small) sections in the Greek Toolbox. This will insert the desired letters into the entry window.
You can also type the name of the Greek letter into your expression, e.g theta. The symbol will be inserted after you press enter. To get an uppercase Greek symbol, capitalize the first letter of it's name, e.g. Theta.