Cleaning
The 3 following controls in Calculator/Controls are never used in the application.

• AppBar: https://github.com/Microsoft/calculator/search?q=AppBar&unscoped_q=AppBar
• OperatorTextBox: https://github.com/Microsoft/calculator/search?q=OperatorTextBox
• OperandTextBox: https://github.com/Microsoft/calculator/search?q=OperandTextBox

TitleBar and TitleBarHelper are used in different parts of the application (Memory, HistoryList, ...), but it seems like these controls have no effects on the app (old code from Windows 8/Windows Phone 8.1?)