onPrintDialogClose - cancel or print button clicked?

The onPrintDialogClose event works well, but I could not find a way to determine if the user clicked the "Print" or "Cancel" button. Can you please add the actual button clicked as parameter in the callback function?

Example:
printJS({
printable: data.report,
type: 'pdf',
base64: true,
onPrintDialogClose: function (e) {
if (e === true) {
alert('Printing done - Print clicked');
} else {
alert('Cancel button clicked');
}
}
});