First of all, there is a lot of differences between the version on the SVN and the one on the Demopage. This confused me a lot when I was trying to figure out this bug.

I couldn't get my calendar to use monday as startingday of the week correctly. Sure enough the header seemed ok, but when I compared the calendar with a real calendar (like the one in Windows) I noticed the starting day was wrong in SCAL. I think I fixed this now, but I leave that for the experts to evaluate.

I changed this line in _buildWrapper

firstDay = (this.options.weekdaystart - firstDay) < firstDate ? firstDay + this.options.weekdaystart : (firstDay + 7) - this.options.weekdaystart;

with

firstDay = (this.options.weekdaystart - firstDay) < firstDay ? firstDay - this.options.weekdaystart : firstDay;

Now, the dates are correctly placed on the right days according to my real calendar.

Please verify this fix!