Not sure if it should be supposed to be fired at the on enter microflow, I would prefer an option to have a on calender click microflow instead. But I got it somehow working by using the HTML snippet from Mendix:
Add it to the page and configure as follows, place the snippet with content on your page:
Append the snippet itself to the desired calender button control, make sure you set the on click microflow to your oe microflow of the datepicker.
After configuring as above printscreen style the default picker so it's displayed overlayed over the button, herefor put the following code to the Style section of your widget:
width: 100%; height: 100%; position: absolute; top: 0; left: 0; z-index: 10;
And after this your onclick of the snippet is fired when you click on your calender.
I hope I can bring this post under attention again, because more then a year later I have the exact same problem again.
WIth a different modeler, 7.16.0, but it is exactly as I described above.
Is there a solution or is Mendix working on a solution?