month-view : correct overflow label position on rtl

The overflow layout displays "Other n events" when there are too much event
that a cell can accomodate.

But on rtl languages, due to the layering out of the cell, the position of the
overflow is not renderend on the mirrored date.

We fix that by mirroring the positon of the day on which the events occur so
that the events can appear on the right day.

https://bugzilla.gnome.org/show_bug.cgi?id=777427

src/views/gcal-month-view.c

@@ -1729,7 +1729,7 @@ gcal_month_view_draw (GtkWidget *widget,
 
           /* FIXME: hardcoded padding of the number background */
           gtk_render_background (context, cr,
-                                 cell_width * (column - self->k),
+                                 cell_width * column,
                                  cell_height * (row + first_row_gap) + start_grid_y,
                                  cell_width, cell_height);
           gtk_render_layout (context, cr,
@@ -1797,6 +1797,9 @@ gcal_month_view_draw (GtkWidget *widget,
               gtk_style_context_get (context, state, "font", &ofont_desc, NULL);
             }
 
+          if (self->k)
+            column = MIRROR (column, 0, 7) - 1;
+
           overflow_layout = gtk_widget_create_pango_layout (widget, overflow_str);
 
           pango_layout_set_font_description (overflow_layout, ofont_desc);
@@ -2081,7 +2084,6 @@ gcal_month_view_motion_notify_event (GtkWidget      *widget,
   days = self->days_delay + icaltime_days_in_month (self->date->month, self->date->year);
 
   new_end_cell = gather_button_event_data (GCAL_MONTH_VIEW (widget), event->x, event->y, &hovered_indicator, NULL, NULL);
-  new_end_cell = real_cell (new_end_cell, self->k);
 
   if (self->start_mark_cell)
     {