GWT: Using JSCalendar with ...

Article written in English, as it will be useful to more people. When using the JSCalendar together with gwt-widget, you might overcome problems, as soon as you specify another than the default english locale. You will not see any calendar, but only a line of "undefined" where the days should occur. Turns out that this is a problem in the calendar-YOURLOCALE.js file (i.e. calendar-de.js for the german translation). The solution is to add a variable in the file, which defines the first day of the week

// First day of the week. Sunday is "0", Monday "1", etc.

Calendar._FD = 1;

Thanks for the drupal issues webpage, where I found the solution.