message: Fix UI is not loading in Safari.
  Use Event instead of DragEvent. Angular/typescript outputs the DragEvent but DragEvent is not available in Safari which causes an error: `Error: Can't find variable: DragEvent`.
diff: @@ -27,7 +27,7 @@ export class DraggableDirective implements OnDestroy, OnInit {
  }
  @HostListener('dragstart', ['$event'])
  - onDragStart(event: DragEvent) {
  + onDragStart(event: Event | any) {
  event.dataTransfer.setData('text', '');
  if (!this.isFireFox) {
  @@ -45,7 +45,7 @@ export class DraggableDirective implements OnDestroy, OnInit {
  }
  @HostListener('drag', ['$event'])
  - onDrag(event: DragEvent) {
  + onDrag(event: Event | any) {
  if (!this.isFireFox) {
  this.doTranslation(event.x, event.y);
  } else {
  @@ -54,7 +54,7 @@ export class DraggableDirective implements OnDestroy, OnInit {
  }
  @HostListener('dragend', ['$event'])
  - onDragEnd(event: DragEvent) {
  + onDragEnd(event: Event | any) {
  if (this.isFireFox) {
  if (event.stopPropagation) {
  event.stopPropagation(); // Stops some browsers from redirecting.
  