Merge improvements to wxGenericCalendarCtrl mouse handling

Closes https://github.com/wxWidgets/wxWidgets/pull/143

src/generic/calctrlg.cpp

@@ -1325,13 +1325,26 @@ bool wxGenericCalendarCtrl::GetDateCoord(const wxDateTime& date, int *day, int *
 
 void wxGenericCalendarCtrl::OnDClick(wxMouseEvent& event)
 {
-    if ( HitTest(event.GetPosition()) != wxCAL_HITTEST_DAY )
+    wxDateTime date;
-    {
+    switch ( HitTest(event.GetPosition(), &date) )
-        event.Skip();
-    }
-    else
     {
+        case wxCAL_HITTEST_DAY:
             GenerateEvent(wxEVT_CALENDAR_DOUBLECLICKED);
+            break;
+
+        case wxCAL_HITTEST_DECMONTH:
+        case wxCAL_HITTEST_INCMONTH:
+            // Consecutive simple clicks result in a series of simple and
+            // double click events, so handle them in the same way.
+            SetDateAndNotify(date);
+            break;
+
+        case wxCAL_HITTEST_WEEK:
+        case wxCAL_HITTEST_HEADER:
+        case wxCAL_HITTEST_SURROUNDING_WEEK:
+        case wxCAL_HITTEST_NOWHERE:
+            event.Skip();
+            break;
     }
 }