From 2c7435a469f66bffc0d164ec0383be8d28982afe Mon Sep 17 00:00:00 2001
From: Catalin <maildus@gmail.com>
Date: Tue, 28 Feb 2017 16:03:49 +0200
Subject: [PATCH] Fix wxListCtrl::HitTest()

---
 src/msw/listctrl.cpp | 70 ++++++++++++++++++++++++++++----------------
 1 file changed, 44 insertions(+), 26 deletions(-)

diff --git a/src/msw/listctrl.cpp b/src/msw/listctrl.cpp
index 54bbef9225..62ad1af893 100644
--- a/src/msw/listctrl.cpp
+++ b/src/msw/listctrl.cpp
@@ -1780,35 +1780,53 @@ wxListCtrl::HitTest(const wxPoint& point, int& flags, long *ptrSubItem) const
 
     flags = 0;
 
-    if ( hitTestInfo.flags & LVHT_ABOVE )
-        flags |= wxLIST_HITTEST_ABOVE;
-    if ( hitTestInfo.flags & LVHT_BELOW )
-        flags |= wxLIST_HITTEST_BELOW;
-    if ( hitTestInfo.flags & LVHT_TOLEFT )
-        flags |= wxLIST_HITTEST_TOLEFT;
-    if ( hitTestInfo.flags & LVHT_TORIGHT )
-        flags |= wxLIST_HITTEST_TORIGHT;
-
-    if ( hitTestInfo.flags & LVHT_NOWHERE )
-        flags |= wxLIST_HITTEST_NOWHERE;
-
-    // note a bug or at least a very strange feature of comtl32.dll (tested
-    // with version 4.0 under Win95 and 6.0 under Win 2003): if you click to
-    // the right of the item label, ListView_HitTest() returns a combination of
-    // LVHT_ONITEMICON, LVHT_ONITEMLABEL and LVHT_ONITEMSTATEICON -- filter out
-    // the bits which don't make sense
-    if ( hitTestInfo.flags & LVHT_ONITEMLABEL )
+    // test whether an actual item was hit or not
+    if ( hitTestInfo.flags == LVHT_ONITEMICON )
     {
-        flags |= wxLIST_HITTEST_ONITEMLABEL;
-
-        // do not translate LVHT_ONITEMICON here, as per above
+        flags = wxLIST_HITTEST_ONITEMICON;
     }
-    else
+    // note a bug in comctl32.dll:
+    // 1) in report mode, when there are 2 or more columns, if you click to the
+    //    right of the first column, ListView_HitTest() returns LVHT_ONITEM
+    //    (LVHT_ONITEMICON|LVHT_ONITEMLABEL|LVHT_ONITEMSTATEICON).
+    else if ( hitTestInfo.flags & LVHT_ONITEMLABEL )
     {
-        if ( hitTestInfo.flags & LVHT_ONITEMICON )
-            flags |= wxLIST_HITTEST_ONITEMICON;
-        if ( hitTestInfo.flags & LVHT_ONITEMSTATEICON )
-            flags |= wxLIST_HITTEST_ONITEMSTATEICON;
+        flags = wxLIST_HITTEST_ONITEMLABEL;
+    }
+    // note another bug in comctl32.dll:
+    // 2) LVHT_ONITEMSTATEICON and LVHT_ABOVE have the same value. However, the
+    //    former (used for the checkbox when LVS_EX_CHECKBOXES is used) can
+    //    only occur when y >= 0, while the latter ("above the control's client
+    //    area") can only occur when y < 0.
+    else if ( (hitTestInfo.flags == LVHT_ONITEMSTATEICON) && point.y >= 0 )
+    {
+        flags = wxLIST_HITTEST_ONITEMSTATEICON;
+    }
+    else if ( hitTestInfo.flags == LVHT_NOWHERE )
+    {
+        flags = wxLIST_HITTEST_NOWHERE;
+    }
+
+    if ( flags ) // any flags found so far couldn't be combined with others
+        return item;
+
+    // outside an item, values could be combined
+    if ( (hitTestInfo.flags & LVHT_ABOVE) && point.y < 0 ) // see second MS bug
+    {
+        flags = wxLIST_HITTEST_ABOVE;
+    }
+    else if ( hitTestInfo.flags & LVHT_BELOW )
+    {
+        flags = wxLIST_HITTEST_BELOW;
+    }
+
+    if ( hitTestInfo.flags & LVHT_TOLEFT )
+    {
+        flags |= wxLIST_HITTEST_TOLEFT;
+    }
+    else if ( hitTestInfo.flags & LVHT_TORIGHT )
+    {
+        flags |= wxLIST_HITTEST_TORIGHT;
     }
 
     return item;