in src/helpers/helpers.ts [238:259]
export function createContextMenuEvent(x: number, y: number): MouseEvent {
let evt: MouseEvent = document.createEvent("MouseEvents");
evt.initMouseEvent(
"contextmenu", // type
true, // canBubble
true, // cancelable
window, // view
0, // detail
x, // screenX
y, // screenY
x, // clientX
y, // clientY
false, // ctrlKey
false, // altKey
false, // shiftKey
false, // metaKey
0, // button
null); // relatedTarget
return evt;
}