Format Register page

[rbaltrusch]

Currently, users must register their data using exclusively text entries. This is not optimal, as it forces the user to enter the data in a very specific format, which is not intuitive (see picture of status quo).

Instead of using a text entry for the date of birth, consider using a calendar widget, such as tkcalendar.

Instead of using a text entry for gender, consider using a dropdown with m/f/diverse.