handle NULL BSTRs as empty ones per Microsoft convention

[wxWidgets.git] / src / msw / tooltip.cpp

diff --git a/src/msw/tooltip.cpp b/src/msw/tooltip.cpp
index 98ef64a1b81f6180fc7c9db8cdb881d04e6c729b..909352209d6e350e7abb96eb6e8a06c4b1363011 100644 (file)
--- a/src/msw/tooltip.cpp
+++ b/src/msw/tooltip.cpp
@@ -40,6 +40,10 @@
     #define TTTOOLINFO_V1_SIZE 0x28
 #endif
 
+#ifndef TTF_TRANSPARENT
+    #define TTF_TRANSPARENT 0x0100
+#endif
+
 // VZ: normally, the trick with subclassing the tooltip control and processing
 //     TTM_WINDOWFROMPOINT should work but, somehow, it doesn't. I leave the
 //     code here for now (but it's not compiled) in case we need it later.
@@ -90,6 +94,17 @@ public:
         hwnd = hwndOwner;
         uFlags = TTF_IDISHWND;
 
+        // we use TTF_TRANSPARENT to fix a problem which arises at least with
+        // the text controls but may presumably happen with other controls
+        // which display the tooltip at mouse position: it can start flashing
+        // then as the control gets "focus lost" events and dismisses the
+        // tooltip which then reappears because mouse remains hovering over the
+        // control, see SF patch 1821229
+        if ( wxApp::GetComCtl32Version() >= 470 )
+        {
+            uFlags |= TTF_TRANSPARENT;
+        }
+
         uId = (UINT)hwndOwner;
     }
 };