Thanks for maecaltaks. In case you plan to put more effort into it, one quick request for change:

The Edit Task window has a Save and Delete button on the right. Please remove the delete button or place it up to the top right of the window.

When I enter the date and push "done" to accept the selected date. Then next I would want to save the task. However the delete button has the exact position of the Done Button of the previous window, thus doing it would be more convenient to have the save button at this position.