items in red have  bugs  and are on jira

calculator https://jira.concord.org/browse/OTK-22

• on ExpressionList, list doesn't accept non alphanumeric characters
• checked the edit button: if the input box is blank the edit is effectively canceled, it checks for invalid formulas.
• ExpressionSymbolList, ExpressionConstantList, and Programmable Calc provide no interactive functionality.
• Add measurement and calc test buttons don't work, tested adding and deleting from the text fields.
• Text fields accept non alphanumeric characters and formatting (tab, return)

calculator_cck

• test dragging the objects, splitting connections, changing the resistance of resistors, adding things from the grab bag, checking voltages.
•  clicking in empty space and on objects, confirming voltage drops.
• calculator functionality?