def boxed_days(self):
        x1, y1 = self.sel_start
        x2, y2 = self.sel_end
        if x1 > x2:
            x1, x2 = x2, x1
        if y1 > y2:
            y1, y2 = y2, y1

        grid = []
        for i in range(x1, x2, 15):
            for j in range(y1, y2, 15):
                grid.append(wx.Point(i,j))
            grid.append(wx.Point(i, y2))
        # Avoid jitter along the edge since the final points change.
        for j in range(y1, y2, 20):
            grid.append(wx.Point(x2, j))
        grid.append(wx.Point(x2, y2))

        selected_days = []
        for point in grid:
            (result, date, weekday) = self.HitTest(point)
            if result == wx.calendar.CAL_HITTEST_DAY:
                if date not in selected_days:
                    selected_days.append(date)

        return selected_days
Compute the days that are under the box selection.
dataset/ETHPy150Open enthought/traitsui/traitsui/wx/date_editor.py/wxMouseBoxCalendarCtrl.boxed_days