disableDays dhtmlXCalendar - problem with bissextile years

i m trying to disable the first and last days of the month, but i have a problem with bissextile years…
if i do:

myCalendar.disableDays("year", "1900-02-29");

will be disabled the first of march! Immagine|524x381


there are 28 days in February 1900

i know, try with 2016-02-29…it will disable 1st march

This is how the javascript Date() object works.
It selects the the “February 28” +1, which is “March 1”

but disableDays shoud disable all days in all years.
what i have to do to disable 29th feb for all years?!

what i need is to disable last day of each month for each year.
how to manage the 29th feb??