I don't think wxWidgets is a strong example for cross-platform success. While admittedly I haven't touched wxWidgets in years, back when I used it, I marvelled

I don't think wxWidgets is a strong example for cross-platform success. While admittedly I haven't touched wxWidgets in years, back when I used it, I marvelled that it worked at all, as the source code was such an utter mess. For example, I found a bug where a class constructor would raise lifecycle change events before the constructor even finished, and the issue was brushed away on the mailing list. Argh.