Returns true if the command can be executed in the current app state.
If this method returns false, the corresponding menu option is disabled.
Executes the command with a given parameter.
The parameter passed to the command is defined by the value of the Menu.commandParameterPath property of the current item. If the Menu.commandParameterPath property is not specified, the parameter passed is the item itself.
Interface implemented by command objects.
For details, please see the Menu.command property.