src/js/pannellum.js
function mousePosition(event) {
    var bounds = container.getBoundingClientRect();
    var pos = {};
    // pageX / pageY needed for iOS
    pos.x = (event.clientX || event.pageX) - bounds.left;
    pos.y = (event.clientY || event.pageY) - bounds.top;
    return pos;
}
function mousePosition(event) {
    var bounds = container.getBoundingClientRect();
    var pos = {};
    // pageX / pageY needed for iOS
    pos.x = (event.clientX || event.pageX) - bounds.left;
    pos.y = (event.clientY || event.pageY) - bounds.top;
    return pos;
}
Calculate mouse position relative to top left of viewer container.
@private
@param {MouseEvent} event - Mouse event to use in calculation
@returns {Object} Calculated X and Y coordinates