[regression] first day of the month is broken for some months

In dateExt.js, in the midnight() function, changing

    date.setHours(0,0,0,0);

to

    date.setUTCHours(0,0,0,0);

fixes the issue. However bug #1198652 is back.
This is basically because the current date in UTC is not necessarily the same as the current date in the user’s location.

To clarify my previous comment: the previous implementation

    Date.prototype.midnight = function() {
        var date = new Date(this)
        var t = date.getTime()
        if (t % Date.msPerDay != 0)
            date.setTime(t - t % Date.msPerDay)
        return date
    }

is strictly equivalent to:

    Date.prototype.midnight = function() {
        var date = new Date(this)
        date.setUTCHours(0,0,0,0)
        return date
    }

However both are wrong, because date is constructed as a local date object, so calling setUTCHours() on it doesn’t make sense.

So the current implementation, as found in trunk, is correct, assuming that midnight is supposed to return the current date at midnight in local time. The MonthView is probably assuming that midnight returns a UTC date.

Interestingly, I can observe the issue with my local time, but if I change my time zone to GMT-7 (US west coast), I can’t see it anymore. There is obviously a mix of UTC times and local times somewhere that messes the view.

Fix committed into lp:ubuntu-calendar-app at revision 75, scheduled for release in ubuntu-calendar-app, milestone alpha-1