From 4177593aef9d50da0a19eb4940be17e883c08cc2 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Sun, 6 Sep 2015 19:40:03 +0200
Subject: [PATCH] Fix vertical wheel scrolling direction in
 wxGenericCalendarCtrl

Make scrolling upwards (positive delta) go to the past (i.e. decrease the
date) for consistency with the native calendar controls.

See https://github.com/wxWidgets/wxWidgets/commit/50daf1feabc42fdd14b534339b4b3bd654a5989c#commitcomment-13087042
---
 src/generic/calctrlg.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/generic/calctrlg.cpp b/src/generic/calctrlg.cpp
index d75758ad75..97db680459 100644
--- a/src/generic/calctrlg.cpp
+++ b/src/generic/calctrlg.cpp
@@ -1519,7 +1519,10 @@ void wxGenericCalendarCtrl::OnWheel(wxMouseEvent& event)
     switch ( event.GetWheelAxis() )
     {
         case wxMOUSE_WHEEL_VERTICAL:
-            span = wxDateSpan::Month();
+            // For consistency with the native controls, scrolling upwards
+            // should go to the past, even if the rotation is positive and
+            // could be normally expected to increase the date.
+            span = -wxDateSpan::Month();
             break;
 
         case wxMOUSE_WHEEL_HORIZONTAL: