Using native comctl32 from XP or so should work and fix the issue. Probably the Wine bug is that Windows programs can override the behavior of the combobox (a lot of apps do this) and since our implementation is not 100% the same as Microsoft their implementation you can encounter issues like this. We try to fix them though, so file a bug report. Mention the Wine version you are using and the app (hopefully there is a demo which shows the problem).
