I recently had an issue with ckeditor inside pop-ups (modals) in drupal 8. I could not edit the fields for entering column numbers and rows inside the table pop-up of my ckeditor. The snippet below fixes this issue. Source:
var orig_allowInteraction = $.ui.dialog.prototype._allowInteraction;
$.ui.dialog.prototype._allowInteraction = function(event) {
// address interaction issues with general iframes with the dialog
if (event.target.ownerDocument != this.document[0]) {
return true;
}
// address interaction issues with dialog window
if ($(event.target).closest(".cke_dialog").length) {
return true;
}
// address interaction issues with iframe based drop downs in IE
if ($(event.target).closest(".cke").length) {
return true;
}
return orig_allowInteraction.apply(this, arguments);
}