week picker accessibility

[HenrikeW]

Try to use the week picker with only keyboard navigation, and with CSS switched off - this is how a blind user would perceive it.

When no CSS is present, the week selection is a bit strange. Selection/Changing weeks work, but is hard to perceive and it is almost impossible to understand that pressing the Esc key brings you back to the normal view. Also, if clicking the week selection, you have to click a date before you can click escape to return. The names and numbers of the days are not sorted, but you can navigate with the keyboard arrow keys + enter to change which week is shown. Sometimes, pressing Enter when a number is selected does not do anything

Improve behavior, button labeling, etc of the week picker. Maybe one way could be to make the weeks instead of the days clickable?

Also, even for seeing users, it's hard to see that something has changed in the background when they have clicked on a week. The week picker should close after click, or the change should only happen after clicking on some kind of "select" button.