modifiersPressed = function modifiersPressed(names) {

        // If any required modifiers are not pressed, return false
        for (var i=0; i < names.length; i++) {

            // Test whether current modifier is pressed
            var name = names[i];
            if (!(name in modifierKeysyms))
                return false;

        }

        // Otherwise, all required modifiers are pressed
        return true;

    }
Returns whether all modifiers having the given names are currently
active.

@private
@param {String[]} names
    The names of all modifiers to test.

@returns {Boolean}
    true if all specified modifiers are pressed, false otherwise.