Comment 2 for bug 1583896

replace the broken .desktop file with this one.

[Desktop Entry]
Name=Calculator
Comment=Solve simple equations
Exec=pantheon-calculator %U
Icon=accessories-calculator
Terminal=false
Type=Application
StartupNotify=true
Categories=GNOME;GTK;Utility;Calculator;
Actions=AboutDialog;

[Desktop Action AboutDialog]
Name=About Calculator
Exec=pantheon-calculator --about