Add error checking when retrieving client data from wxMSW wxListBox.

Verify if retrieving client data failed which might happen if the index
is invalid for example. This makes code more robust and also consistent with
wxChoice.

Closes #13883.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70415 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

diff --git a/src/msw/listbox.cpp b/src/msw/listbox.cpp
index 69565096f7b90a0fd9dc8c3cea7892829375b4fc..fd17da4b4177f57c1f995954b38b48d646106ec2 100644 (file)
--- a/src/msw/listbox.cpp
+++ b/src/msw/listbox.cpp
@@ -306,7 +306,15 @@ bool wxListBox::IsSelected(int N) const
 
 void *wxListBox::DoGetItemClientData(unsigned int n) const
 {
-    return (void *)SendMessage(GetHwnd(), LB_GETITEMDATA, n, 0);
+    LPARAM rc = SendMessage(GetHwnd(), LB_GETITEMDATA, n, 0);
+    if ( rc == LB_ERR && GetLastError() != ERROR_SUCCESS )
+    {
+        wxLogLastError(wxT("LB_GETITEMDATA"));
+
+        return NULL;
+    }
+
+    return (void *)rc;
 }
 
 void wxListBox::DoSetItemClientData(unsigned int n, void *clientData)