Focus trap inside Calendar

[WiktorHejman]

When navigating through the calendar using the Tab key, it's impossible to move the focus beyond the day/month/year panel, for example, to shift focus to the confirmation button placed below the calendar.

[ztarpley]

I second this, although I'm able to reverse tab (Shift + Tab) away from the Calendar. It only appears to be the forward tabbing that is trapped. v4.5.1