Extend datepicker to fill calendar with pre-existing dates and highlight them....
what I would want to have is a functionality, where I can define certain groups, assigning them a specific colour, then, in a second step, assign certain dates and names into those groups.
If the calendar shows such a date, it should be marked by the colour provided for it's group and show the name as a tool tip on mouse hover.
If a date appears multiple times, each name should appear in the tool tip in a new line. And maybe there should be a hardcoded background-colour implying "multiple", if any given dates appears in more than one group.
The background is easy. I want to mark different dates, with different colour for the different users that chose them, but don't want to prohibit any other user to pick them. So the colouring and the tool tip are just for the information of the user.