Fixed some little bugs.

 On branch master
 Changes to be committed:
	new file:   build-calculator-Desktop-Debug/Makefile
	new file:   build-calculator-Desktop-Debug/calculator
	new file:   build-calculator-Desktop-Debug/calculator.o
	new file:   build-calculator-Desktop-Debug/main.o
	new file:   build-calculator-Desktop-Debug/main_window.o
	new file:   build-calculator-Desktop-Debug/qrc_qml.cpp
	new file:   build-calculator-Desktop-Debug/qrc_qml.o
	modified:   calculator/calculator.cpp
	modified:   calculator/calculator.pro.user
	new file:   calculator/calculator.pro.user.73863d4