You still don't get it, every OS release make changes of how widgets behave. One example, OS X "natural" scrolling behaviour, you run and old QT application on that platform and I am sure it will not behave the same way and users notice that. QT developers are good chasing every tiny update OS providers do, that doesn't mean that old applications are updated automatically. All applications need to be updated, specially on Windows and OS X where there isn't a shared QT runtime. If WPF is the new native, I am pretty sure that any modifications Microsoft make to old widgets are added to the new ones because I don't think they want an inconsistent experience for their users (sometimes I think they don't care after Windows 8)
I still write a lot of Java Swing code, so I know custom drawn toolkits have their advantages, if you are a good developer using them, and I am not against what QT do, I am only saying that QT are not native controls (only on platforms where it is the platform toolkit)
Is this QT or GTK? http://tirania.org/s/138c98b8.png
It is GTK, do GTK use native controls? NO