The calendar view, both in datebox and calendar components, is not working properly when you use the "next month" button (>). Normally on such a month change calendar preserves the day number if possible, so for example if you select 10th of January and click next month button then the date will change to 10th of February. However if the year gets changed as well i.e. if you change from December to January then the day number is not preserved and is overridden by the last day of the month. Both next and previous month buttons are affected.
How to reproduce:
Open the calendar and select the 1st day of November. Click on the next month button and the date is 1st of December. Click on the next month button again and the date is 31st of January - day number was changed.