A problem about mini calendar

The link of online sample is below:
If I press the “disabled” button,
,then I click the text field which will show the mini calendar, the problem occurs. The mini calendar will be hidden and can not display itself completely.

Does anyone know how to fix it?

In current version the behavior of datepicker is hardcoded. It is always shown at bottom of date field.

Unfortunately there is no easy way to change it