And that's why the Wireshark guys are moving to Qt. As long GTK keeps other platforms as second (or third) citizens they will keep losing market share.While GTK+ 3.10 is the latest stable release, today's Windows release is of GTK+ 3.6.4.
gtkwin32theme.c, QWindowsXPStyle and QWindowsVistaStyle.
GTK+/Qt widgets look like native but it is impossible to use native Windows Controls API with these widgets because it is not really native. It is a key difference between GTK+/Qt and wxWidgets approaches.
How exactly is GIMP not native-looking? The only thing that comes from GNOME are the icons, and the reason for that is obvious. The only difference I have noticed between it and native Win32 apps is that the menu item hover effect becomes all blue at times.