[Bug 31076] WinDirStat problem after clicking on file in graphical analysis

http://bugs.winehq.org/show_bug.cgi?id=31076

--- Comment #10 from Nikolay Sivov  2013-01-09 16:13:17 CST ---
I think I understand a problem now. When you click on graphical dir view
(whatever it called) it's possible it will need to insert new item to a list.
And here is what happens:

- LVM_INSERTITEMA with item lParam containing pointer to internal application
  data (CSortingListItem* pointer to be precise);
- our handler eventually calls LISTVIEW_ShiftIndices() that also changes focus
  item and could trigger a repaint if list scrolling is needed;
- scrolling repaints window with UpdateWindow() so winproc is called with
  WM_PAINT synchronously while we still process LVM_INSERTITEMA;
- repaint operation needs item data to paint, so it queries notification
  window (application) with LVN_GETDISPINFO, but at this point lParam
  is still not set - it's zero from Alloc().
- application casts it to CSortingListItem* and calls it's methods without
  checking for NULL.

To confirm this I commented LISTVIEW_SetItemFocus() call from
LISTVIEW_ShiftIndices() and it made crashes go away. It's a really serious
problem that could potentially affect a lot of applications, I need to think a
bit more what a proper fix would be.